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Foam Sculpt and Scale Halloween Monster Props

5638 Views 1 Reply 1 Participant Last post by  Terra
Note: This is a repost of an old tutorial whose links to pictures were broken with the software update at HF.

This tutorial will show how to design, cut, carve, sand, scale and paint a prop made from foam. It will follow a Hellhound build made for our 2012 haunt. The Hellhound is a static yet intimidating prop. If it was real monster it would measure 10' nose to tip of tail. The prop's tail is curled so its actual length is 8' but the height is still the same 41' at the shoulders.

Designed to be outdoors in the cemetery. It is fluorescent so it glows with UV, purple or blue LED lighting. The design of the Hellhound is based off of Miles Teves' incredible concept art for the movie: Chronicles of Riddick.

As usual, here's an overview video to help you see how a build like this will be like.

Let's get started...

Materials List:
2" pink or blue foamboard
Foamboard glue – Loctite PL300
Glidden Gripper
Exterior flat latex paint
Airbrush paints
Gloss airbrush paint
1" PVC
Wood putty
Spider Hill Prop Works Spider Joints: http://www.spiderhillpropworks.com/Spider-Joint_p_13.html
Spider Hill Prop Works Universal Mounting Bases: http://www.spiderhillpropworks.com/Universal-Mounting-Base-_p_47.html

Tools List:
Industrial Hot Knife or jig saw
Jig Saw
Caulk gun
SureForm shaver
Pottery tools
Paint scraper
Sander like a Dremel Multi-Max
Dremel with grinding bits
Blue painter's tape
Small sheet of Plexiglas or glass
Overhead marker

Scale Model: The best help with this sculpt is to have a small-scale model in the pose you need. Got lucky with the Hellhound because there happened to be a toy model of it. Geeks and their action figures! The closer your scale model is to what you need will make everything easier. Worse case, sculpt a smaller version if you have to. You can get lost in the sea of foam so this model helps to keep you focused because you are carving such a large creature.

Project: Take a picture of the side of the toy. Be sure your camera is straight on the model - anything off will just make matters worse as you blast it full size. Project the image onto a sheet of 2" foam using a projector. Adjust the image on the foam until you get the size of monster you are looking for. Trace the outline of the image onto the foam using a Sharpie. Note: perspective can be tricky so be aware that the image is 2D and you are making a 3D monster. In 2D (picture) the far away legs are smaller but when you make it 3D you have to make them the same actual size as the legs close to you on the picture. So, exaggerate the size of the back legs as you trace it out. Hope that wasn’t confusing. Look at it this way, if you trace the legs exactly as they are in the picture – the foam won’t be large enough on two of the legs and they will look like chicken legs compared to the other two.

Determine Number of Boards: Look at the top of the model and see what the widest point is on the model. Measure it across and note the measurement. Move the ruler to the side of the model that is the same side that's projected on the foam. Have the ruler start the measurement from the table up. Note where the top measurement now sits on the profile of the model. Walk over to the projected image on the foam. Mark the same spot that you just noted on the model. Grab a ruler and measure from the floor to where you just marked. That will tell you in actual inches the width your monster will be. Just divide that by the 2" foamboards and you now know how many sheets you'll need. So, if the creature is 16" wide then you will need eight 2" foam boards. Pull out that wallet - you're gonna need it.

Cut out Sheets: Mark an outside perimeter about an inch out from what you just outlined on the foamboard. Use a jig saw or the 6" blade on the Industrial Hot Knife to cut out your first sheet. Transfer that to the other sheets, mark and cut out. Rinse, repeat, drink.

Mark Top Outline: Surround the model with something (wood, books) that allows you to set Plexiglas or a glass sheet over the model. Place a flashlight near the front to help illuminate it. Trace the top outline of the model on the glass using an overhead marker. Take a picture of the outlined glass. Stack up the cut foam pieces in front of the projector. Project the top outline image onto the foam and trace out.

Mark Side Outlines: Use blue painter's tape to hold all the foamboard pieces together and put the monster up on its feet. Position the model so you can refer to it while you trace the outlines for the front and back of the monster. Now you should be better able to visualize the creature from all sides when you start carving.

PVC Support: You will need additional PVC support if your monster is big or will be outdoors to help fight the wind. You can also use PVC support to allow mounting for a removable tail, tentacle or head if you need to break your monster down into something smaller for transportation. Spider Hill Prop works sells two types of PVC connectors that will make this task a whole lot easier. The first is called Universal Mounting Bases. These bases allow you to attach them to a plywood base using screws securely. These bases hold 1" PVC pipe. The other joint is called a Spider Joint and that's used for easily deciding on angles or to have an area where you can attach and detach those removable parts like a tail. You don't have to go overboard with putting in a PVC support. The Hellhound used two supports. One for the front right leg/shoulder and one for the back right leg that continued to where the tail would attach. The tail used 1/2" PVC so a 1" to 1/2" conversion connector was used.

Decide on PVC Placement (picture 1): Draw on the outside of the foam where the PVC should go. Look on the top of the monster to see which foamboard the PVC should be embedded. This is important because if you don't have it centered inside the foam you are carving - the PVC will show as you carve it down. Try to get it into the center of a leg or something as best you can.

Plywood Bases: Even if you are putting PVC in only some of the legs you will still need plywood bases for all the legs to keep the monster level and have better support. Leave enough space on the plywood so later on you can cut 1/2" holes for attaching a rope to tie off to tree stakes in the yard just as you do for tombstones. Cut the plywood out with a jig saw and set aside.

Cut the PVC (picture 2): Grab the foamboard that the PVC will be embedded into. Redraw where the PVC will go and start to build the PVC support. Attach a mounting bracket onto the end of a 1" PVC pipe and determine how long the first piece of pipe should be cut before you need to attach a Spider Joint. Attach the Spider Joint and then see how much pipe you need for the next line. Keep doing that until you get the PVC structure you like and set the joints in place tightening the joints and then make very secure by using set-screws. Dremel out the inside of the Universal Mounting Base to make it a bit easier to remove later on because you haven't carved the foam yet, you don't know where the plywood will be permanently attached so you will be removing that base after painting. You don't want it too tight and nearly impossible to take off again.

Channel PVC Channels and Glue: Next step is to cut out channels of space for the PVC. You can use a Dremel and chip it out like for tombstones or the Hot Wire Knife with the sled attachment. Place foamboard glue (PL 300) into the channel and set the PVC assembly in place. Use bits of extra foam to help tighten and firm up the channels because you don't want that PVC wiggling around. Add some more glue to set those pieces up. Allow all of this to dry overnight. Foamboard glue needs air to dry.

Glue the Layer Cake (picture 3): heh - layer cake - but that's what it looks like. When this monster was built there was a painful lesson learned. Foamboard glue (PL 300) needs air to dry. The problem is there is so little (or no) air once you sandwich the foam together. When you are carving and hit an undried section of glue it will gunk up your rasp. Also, while you are carving you may carve into a section that there isn't any glue and the piece will just fall off. After these frustrations a video was made testing and explaining the shortfalls of many glues that can be used to glue foam. In the end, I suggest using Glidden Gripper to glue the layers together. Here is that video:

Paint both sides of foam with Glidden Gripper and line up with the other foamboard sheet underneath. Press down all around (you can step on it). Repeat until all the layers are stacked up. Weigh down with heavy objects and/or rope together if unable. Allow to dry for as long as you can (weeks would be great). This does glue up great on the edges within 24 hours but if you are carving deep into it – you may run into pockets of wet glue. It’s not the end of the world though – it won’t gunk up your tools like if you hit PL 300. Remember – Glidden Gripper is a lot like paint. Now, if you need this glued sooner – consider using Great Stuff – yeah, it is messy and more difficult to control but dries within 24 hours and was the runner up in the test.

Carve: Whoo Hoo - the dreaded step is here. But, no fear! Carving/sculpting isn't as hard as you may think or I did at one time. One day I got the most valuable piece of art advice ever. It was from Scourge - the owner of TheSkullShoppe. He said, "You carve away what doesn't belong." That is what you need to remember. This is where that scale model comes in so handy. Look at the model and look at your monster and carve away what doesn't belong. Do this in sections and make the first pass just rough cuts. This will help you get good angles.

Here's what was done for the Hellhound: Carved the back to get the right height. Carved the neck. Carved the front right leg and kept hitting it on different sides all the while looking at the model as a reference. Sometimes it helps if you mark off where you think you need to cut. That helps you visualize better. Did the left front leg next because you will remember what you similarly did for the other leg. Did the back legs. Finally carved the head but kept the placement of the eyes by re-marking it if the previous mark was cut away. This helps with reference. Next, focused on the ears... Remember, as you do each section you don't have to carve for perfection. Just get it to a good place and then move on. Did the entire monster in these sections and then repeated again but this time getting more detailed. Make pass after pass until you've gotten to the point that you can't find any more sections that has parts "that don't belong."

That's how you carve but with what? There are many ways but here's two: The first is what was explained in the Demon Horse tutorial - drywall saws, wood rasps and other toothy tools. The other is using an Industrial Hot Knife. Here the Hot Knife was used. Bend the round wire into a rectangular shape as shown in the picture above. This allows you to carve away strips of the foam. Be sure to PULL the Hot Knife through the foam - not push. It makes smoother strokes.

SureForm Smooth: Use the SureForm shaver to rasp smooth the entire monster. This will knock down the high ridges and allow you see the structure of the monster better. Use a scrubby for the tighter areas. This takes a lot of time so be patient here. There is a patience tonic I'm thinking of right now...

Detail Carving: Mark what needs to be carved like the feet, face or teeth. Then use pottery tools to pick away the design you are after. Use pieces of scrubby to sand in the tight corners. Use a small grinding bit attachment on the Dremel for carving out thin lines like between the fingers, the ear folds, cuts for the eye socket and the nose.

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Temporary to Permanent Attachments: Use the same procedure for temp/perm attachments as you just made the body. Used a string that was the exact measurement of the tail on the model and transferred it to the body of the monster. Because we know how long the body of the monster is you can determine how long the attachment needs to be.

If you need a rounded PVC shape you can shape it by bending PVC gradually using a heat gun while bending over a round object (like a 5 gal. bucket). Let cool in place. Pictured is 1/2" PVC. Here's a tip told to me after this monster was made: if you fill the PVC with sand – it will bend in a better arc and not fold.

Sheath the PVC in foam, carve and smooth down with the SureForm shaver.

Mistakes (picture 1): Sometimes you carve too much away or there are voids that need to be filled. There are several ways to fill them but all of them aren't as good as the original so try to avoid this as much as possible. Options: fill with layers of foamboard glue, mixture of glue with pink snow and ‘air dry’ clay. The ‘air dry’ clay is the easiest to sand back down to a smooth surface, but you'll never match the original texture with any of these methods. Luckily, once you base coat the creature it's pretty hard to tell. whew!

Super Smooth Sanding (picture 2): Shave any new areas that haven't been knocked down yet with the SureForm Shaver. Next, use a small electric sander like a Dremel Multi-Max to give a final ultra-smooth surface to areas that need to look like skin. This takes a lot of time and makes a lot of dust. Get to drinking early. For the hard-to-reach areas - use a scrubby.

Plan Scales (picture 1): Place your monster in front of the projected image again and trace out the scales. This will give you a reference for the direction and the size of the scales.

Make Scales (picture 3): Place a piece of paper over one of the largest traced out scales and mark the outline with a marker. Cut the paper out and then place the design on a scrap piece of 2" foam. Cut out with a Hot Knife. Place that piece on its side and slice away like you are slicing bologna. Remove the front and back pieces and separate the remainder. Mix up and place in a pile.

Make Variety of Scales (picture 3): Take the paper design and mark a slightly smaller shape and cut that out. Trace that onto the 2" foam and cut out the scales just as you did for the first set. You will continue to make more variety of sizes but also make different shapes. Make teardrop-shaped ones for more spiky looking scales. You can also make skinnier teardrop scales that are more like spikes.

Make Back Spine Scales: These are more challenging. Most scaly monsters have their scales ending up into spiky back spine scales. Carve a triangular shape as shown above. Carve out the bottom in a curved ridge shape so it matches up with the curve of the monster's spine. Keep carving it until it sits flush on the monster. Mark the dead center on the top of the spine for reference. Carve at that marked center and angle away to the far edge on both sides. It will now start to take on a spiky appearance. Cut away the front so it slopes more. Trim the front edges from the top down to give it a chiseled appearance. Do the same for the back of the fin. Do this in varying sizes going from smaller to larger and then back down to smaller.

Applying Scales: Scales have a pattern. You start to apply the scales from the back of the monster to the front. The first layer is applied one next to the other in a row. The next layer is placed over the seam of the first layer and overlapping halfway. Use PL300 foamboard glue to attach the scales.

Adjust the size and shapes of scales while you are applying. For example, you are using the largest scales on the belly and graduating down to the smaller ones as you reach the shoulder. You are also changing up from the circle shape to more of the teardrop shape as you reach the neck scales. For in-cut muscle lines you also want to graduate to smaller scales so the muscle cut is visible. The legs and arms are using much smaller scales and the leg scales are scales that are flusher to the body. Make the scales flexible in order to have the scales become flush with the skin. Pound the scale with a hammer on each side and all over the surface. This will compress the foam and allow you to form it with your fingers so you can manipulate it. Now you can make the scale flusher to the body. You can also do this same procedure to bend the scale, so they hold a curve and appear more spiky like what you see on the neck.

Clay Accents: Clay will allow you to ease the transition from foam scales to the skin. Clay also can be sheathed onto areas that need more of a solid look like the eyes, teeth and claws. Paperclay is a great clay for this work. It is an ‘air dry’ clay and you can get incredible detail.

Draw out areas where you need to make smaller scales or bumps. Take a bit of clay and knead with some wet fingers to make it smoother and more pliable. Wet the area where you'll be placing it and smooth into place. Wipe with very wet fingers as the final forming step for sections that needs the surface to be very smooth like the teeth, eyes and claws.

Skin Lines (picture 1): Skin has many cracks and lines in it. Draw in those cracks and lines with a Sharpie. Use the cone-shaped grinding Dremel bit to carve them out. Draw a second series of thinner lines and use a thinner grinding stone.

Final Readying (picture 2): Carefully inspect the monster. Look for any openings between the foam sheets and fill with wood putty. Repair any place where the foam may not be all the way glued.

Drylok Bases: Paint the wood bases on both sides twice with Drylok. When dried, place under the monster where they'd normally be to help steady it for the next step of painting.

Base Coat: It is faster and easier to use a spray gun for this step. Pick the color needed for your monster in exterior latex flat paint. Follow the spray gun's instructions for thinning the paint if needed. I use a Husky Pro HDS500 Multi-purpose Spray Gun from Home Depot. Each round of spraying used 3 cups of thinned paint (18 oz. of paint + 6 oz. water) sprayed at 40 psi. You will probably need a spray booth of some sort or do this outside. Try to spray everywhere you can on the monster. It may be helpful to prop it up to better spray underneath. After the first coat has dried - check for any open seams that you first missed with the wood putty and apply some more. Also use a flashlight to check for any areas you need to concentrate the next spraying on. Allow the creature to dry between each spraying session. A fan helps here. Just before the last coat, put some of the paint in an airbrush and spray in areas that the spray gun can't reach. Do a final coat with the spray gun. The Hellhound here took a total of 6 coats and nearly a gallon of paint.

When you are done you should notice a wonderful texture that the spraying left behind on the scales yet still kept a great skin texture.

Detail Painting: Use an airbrush to paint the details. A light brownish-yellow paint looks good for claws and teeth. You may have to hand paint some areas if the over-spray would ruin any areas like the red inside a mouth. Use black in the airbrush to shade areas like between the teeth or darken the claws where is comes out of the skin.

Glossing: Use clear gloss paint for any areas that would glisten with moisture or shine from use. Pay attention to the nose, mouth, eyes, tear ducts, ears, spine, knees, elbows - places like that. You may also want to gloss up the claws and teeth.

Mount to Bases: Remove the plywood bases and the Universal Mounting Bases from the monster. Use a scrubby to remove any paint drippings from the bases. The previous painting step should have left clues where the screw holes need to be placed permanently and where the monster needs to be glued. Screw the Mounting Bases into the plywood and drill out 1/2" holes in a couple of corners. These holes can then be used to tie off the platforms to tree stakes in the yard to give it extra stability from the wind. Touch up with paint. Replace the bases back on the monster and glue in if it's just feet to plywood instead of PVC. Where it was PVC to Mounting Bases - use self-tapping screws to secure.

Removable Parts (not pictured): Screw in any removable parts once you get the monster where it needs to be on Halloween. You can then caulk and paint to disguise the seam.

And you are done! Yeah and pat yourself on your back.

Here's a short video just showing the completed Hellhound:

Thanks for checking out this tutorial!

Video in the graveyard:

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