Thread: Technological Tombstone of Terror (build log/tutorial)

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This is the tutorial/build log for my "Technological Tombstone of Terror" which is shown here:



Part 1:

A few people expressed interest in a tutorial for how I built by video/laser/LED tombstone. So here's the start of it!

In the basic sense it's just a standard pink-foam tombstone. It's built up using multiple sheets of foam and some carving and routing, then decorated with some other commercial bits (skull and bones from a "bag of skeleton", some pre-cut wood scrollwork from HomeDepot, etc.) I finished it with monster mud and Drylok, and painted with acrylic using a paintbrush and airbrush. I won't go too in depth on all the techniques since I believe they're adequately described and shown online (this forum, Youtube, etc.)

I started off by making a detailed design specification for what I wanted to construct:


Ok, so that's really more like a scribbling on a post-it note. The point is to at least put down enough that you sort-of know the look you're going for and can be sure you have whatever pieces you want on hand.

I set about converting my sketch to a simple outline on a piece of cardboard. I knew I wanted a full-size skull, so I traced a skull on to the cardboard to use for the 'scale' of the piece and built the outline up around it.


I used some basic measurements (6" across for the skull) to then measure (roughly) the relative sizes of the features on the drawing and convert them to Sharpie outlines on the cardboard. When it came to making curves, I took part of an old metal coat hanger and bend it in to half the shape I wanted-- then just flipped it around to make an exact duplicate going the other direction and simply traced it on to the cardboard.


Using an X-acto knife and a piece of steel (to keep a straight edge) I cut out the cardboard outline and got a good feel for the size of it. (It's about 4' tall.)


I didn't care for the 'horns' on the side as much when I saw them 1:1 (too many points lining up on the edge-- looked like it was trying too hard). I ended up cutting them off and then set to transferring the outline on to the pink foam board.


Pretty much anything can be used to cut out the foam-- I happened to have a Fein Multimaster which I used. Hindsight being 20/20, I would recommend cutting the foam in to equal sized pieces, tracing the shape once on to the top, and then cut the entire stack all at once. I ended up with a lot of *slightly* different sized pieces doing it one at a time which cost me some extra time to trim and sand up. I used 1" thick foam for three pieces and 3/4" for a fourth piece. (The thinner section is for the front-most piece.)


(Labrador included for scale. )

To make my 'crossbones', I took one foam femur bone (from the Halloween section of a local grocery store) and cut it in half length-wise. I set the bones out (along with some other little wood accents I found for a few bucks at Home Depot) to see how it looked. Size and everything looked good:


Taking the thinner (3/4") piece of foam, I cut the top 'window' and the bottom 'relief' section. I then used a wood router with an edge bevel bit to route in some detail along the edges. Once I saw how nice the router worked, I took another piece of scrap foam and made a little 'ledge' for the top window. The router's fun, but I'll be vacuuming pink foam dust out of the garage for the next year.


Again I put the 3/4" piece on top of one of the 1" pieces and arranged the trim bits how I liked them. The wood details were in the molding section of Home Depot-- ran maybe $4-5 each. Seemed like a bargain vs. trying to carve them myself!


Next I set about the pentagram. I used Photoshop to rough up a pentagram image I found on the web (just using a combination of 'noise' and 'blur' filters and selections to make it look a little 'chewed up'.). I scaled the shape to the size that fit the space available and printed it 1:1. Using a small X-acto I poked holes around all the black areas on one of the 1" thick sheets of foam to give me a guide for where to cut. You could really do that any number of ways-- tracing paper, freehand, a projector, etc. At the same time I decided to carve a little relief for where the round accents go-- that way they sit down in the foam a bit and nicely line up with the carved front faces. Keeping various surfaces at different depths help give the piece some character and make it seem more imposing.


With the outline traced, I used a Dremel mototool with a ~1/4" diameter router bit to cut away everything between the dotted lines. Although I didn't measure, I tried to keep the depth consistent just by routing only as deep as the cutting surface of the Dremel bit.


My 'ah-hah' moment came next. It occurred to me that I could use the router (with a ~1/2" straight end mill) and set it to an exact depth almost, but not quite cutting all the way through from the *back* of the same piece of foam that has the pentagram carved in to it. I proceeded to route out the area behind the pentagram after setting the router depth by eye-- I was probably between 1/16" and 1/8" away from breaking through the foam.


Pleased with myself, it dawned on me that if I cut through the foam the rest of the way, there was nothing to support the 'floating' parts of the pentagram. If I didn't cut through all the way though, the backlighting would likely be pink and/or very hard to get the right 'burning' effect. Grrr. After thinking about my quandary for a bit I had the solution. I could place a piece of plexiglass (thickness not important-- I used 1/8") on the back and glue the pentagram bits to the plexiglass, then cut away the remaining foam from the front and be left with a transparent pentagram, but with the pieces firmly held in place. Since plexiglass is much easier to cut in rectangular shapes, I changed my routing to be square and stuck a piece of used, clear plexi inside. (You could use opaque or colored plexi too depending on the look you want.)


The next steps happened quickly and largely just by way of "hey! new idea!". I had originally planned on making the 'fire' behind the pentagram using some foam, LEDs, etc. similar to the 'cauldron coals' other people have shown how to make. BUT, I didn't have enough time to do that right. Instead, it dawned on me that I could mount an old LCD computer monitor behind the shape and play an actual video of fire burning. Much better! (If you decide to implement this-- you would be well advised to consider how big and in what orientation you want to mount the monitor *before* making the tombstone shape! I lucked out and ended up with a monitor size and orientation that fit the design! Goodwill, eBay, and other used stores often have old LCD monitors for $20-40.)


(A couple notes of the above picture-- you can see the plexiglass glued in place holding the pentagram bits. You can also see that I cut away the rest of the foam to reveal the pentagram. If I had that to do over again I would have left the thin foam barrier in place until *after* I had put the first coats of paint on! Since I'd already cut it out though, I had to be extra careful while painting to not get paint on the plexi. That was a PITA. Also, when you cut out the top 'window' in the pieces that stack together behind the front face, make it about 1/2"-3/4" larger diameter. That leaves room to block the laser beam and hide some LEDs from view when we get to the wiring stage.)

I had a monitor that fit right, so I proceeded to place it face-down on the foam and trace the outline. Then, using the router again I made a shallow 'pocket' for the LCD to fit inside. The LCD was over 2" deep, so I then made an outline on another of the 1" thick foam sheets and simply cut it out so it would sit around the screen. This picture shows the two sheets stacked on top of each other with the LCD sitting down inside the 'pocket':


With the monitor situated (it's actually snug enough to stand upright and not fall out!) I returned to the thin, 3/4" front face. I used some more scrap pieces and the router to make some eaves and decoration for the top and then drew in some cracks using a Sharpie. Since the piece is (relatively) big, I actually added a lot more cracks and weathering later, but this was the start:


Since I'm an electronics-type by trade, I decided to use an old soldering iron to 'draw in' the cracks. You could use whatever you want (knife, wood burner, whatever), but I really, really liked the soldering iron. It makes for a nice organic edge and it seals the foam as you go along-- no little pink foam burrs getting in the way-- and no dust:


With all the necessary cuts done, I then used a hot glue gun to glue the thin (3/4") and two 1" foam pieces together (remember to check the order-- carved shape in front!). A word of caution with hot glue and the foam-- I had to use the 'low' setting on my glue gun or else the hot glue would melt the foam. The hot glue is also kind-of thick, so it's hard to get the pieces to sit perfectly flush without gaps in between. If I were to do this over again, I'd probably try some spray adhesive like Super-77 or something. Some sprays might eat the foam though, so best to test first or seal the foam with some paint or something before gluing.

The monitor just sits inside the 'pocket'-- so it can be removed as necessary at this point, but it's snug (and heavy) enough to stand upright on its own now. (I put another piece of foam behind it for a kick-stand, just in case.)


After getting it propped up, I glued the 'front' pieces on. I found it easier to get things to line up right seeing it in a vertical orientation. When it was laying flat I was having a hard time getting the bones and stuff 'even'. With everything in place, you can plug in the monitor and (using whatever you want to feed it from-- computer, DVD, iPod, media player, etc.) make sure it's all working:


(Edit: I'll add a little more info about the weathering I did to the foam... I used some 80-grit sandpaper to rough the foam up, but honestly I think most of that just disappeared after the application of the Drylok paint later on. I *did* do little random soldering iron 'gouges' all over. I moved the iron above the foam at about 1 foot/second and every once in a while just dabbed it down in to the foam at random intervals and different depths to make some 'wear and tear'. Seemed to work well. You can also see the amount of additional small cracks and fissures I drew in with the iron. Lastly, on all the pentagram I used the iron to cut little 'scallops' along all the edges to make it look like it was chiseled out of the stone. Will anyone notice that? No, not a chance, but I thought it was a nice touch.)

[End of Part 1...]

Fantastic! Looking forward to part two now.

I love the technology built into this, great job.. my reason for commenting though is the atom in the background count me as salivating lol

Originally Posted by guitarist155

I love the technology built into this, great job.. my reason for commenting though is the atom in the background count me as salivating lol

Hahah... Good eye! Yeah, this time of year it's primary use is "Halloween prop holder-upper". It *is* terrifying though, so I guess sort of appropriate here too.

Part 2:

I wanted to use the third (and final) 1" thick piece of foam as a removable (if need be) back 'cover' to the prop and LCD panel. The front three pieces are already glued together (3/4", 1", 1"), so I placed the final piece on the stack and sanded the outer edges with some ~150grit paper to make them more or less all even. At this time I also took a drill and a ~1/4" bit and drilled six holes through the back side around the perimeter (location isn't critical, but I tried to keep them near the edge and in thick sections of the foam). The holes will be used to secure the pieces together without gluing them using the following steps.



I removed the last piece of foam (which we're using for the back cover) and set it aside. Looking at the back of the main tombstone (with the LCD inside) I then took a soldering iron to the holes made by the drill and enlarged them to about 1/2" diameter.



Using some 1/4" bolts as a guide, I put a couple of hex nuts on the end of each bolt-- just tight enough so that both nuts can still turn. I ran a bead of hot glue around the nuts holding them together, and while the glue was still hot...



...pressed the nuts+glue into the holes that had been enlarged by the soldering iron. This makes threaded studs for bolts to screw in to. They're fairly sturdy, but you really don't want to go much more than finger tight with the bolts when you attach the back panel. The following photo shows the nuts glued in place (and a couple bolts too).





At this point I attached the 'back' (it also has a smaller cutout where the monitor was still pretty deep) and started using monster mud (drywall joint compound + latex paint) to paint around the foam and hide the seams from the sheets and the various glued-on decorations.

A couple notes here-- the monitor will get warm in there, so you might want to cut some air vents in the back. I left part of the monitor exposed (and Halloween here is cold; probably in the 50's) so I wasn't too worried about heat. Similarly, if you want the back panel to be *easily* removable, you shouldn't monster-mud it together with the other three. (Instead, use some tinfoil between the layers so it will pull apart easily.) For mine, I was OK with the monitor being 'captive' forever and removing the back would cause some damage to the edges that would require paint touch-up-- but I'd only need to do that if the monitor died.

At this point the system should be pretty water-tight once the edges are mudded and additional paint goes on. This isn't a great rainy-weather prop, but you could add a little more flashing and stuff to protect the monitor on the back further if your back panel doesn't totally enclose it.

Here you can see the back piece on and the start of the mud. I used short (1.5" bolts with large washers) to prevent from tearing up the foam:


I had the edges pretty well sanded down and there wasn't too many large gaps in the front decorations, so I only used monster mud in two applications just around the areas I wanted to 'fill'.


Next, since everything it nicely bolted together I was able to lay the prop down to make it a little easier to work on. I cut another short piece of foam and beveled the edges and attached it to the base of the tombstone. It's just a cosmetic piece to give it yet more depth. My final piece of scroll work went down there as well, along with some additional cracks and distressing.

Like I mentioned before, I should have waited to cut the last foam out from the pentagram, but since I'd already done it I had to carefully hand paint that area. At this point I switched to using Drylok with some black acrylic paint mixed in for a neutral gray tone.


From here on out, it's basic tombstone finishing 101. Two coats of the gray Drylok:


Some drybrushing with a lighter grey acrylic and some staining with watered down black in the cracks and crevasses:


And finally some airbrushing and a similar paint treatment on the skull:


That's pretty much it for the 'tombstone' portion. Next up is the laser and LED lighting!

[End Part 2]

Part 3:

Next up is creating the LED lighting and Laser Vortex effect. There's various ways to create a laser vortex. The simple/cheap type is to just mount a small mirror on the end of a motor shaft at a slight angle and bounce a laser off of it. Google "laser vortex how to" and there's plenty of online tutorials for the details. Mine isn't very different.

To keep the laser system small, I used two mirrors and a green laser 'module'. For most applications, just using a green laser pointer (a couple dollars on eBay) will be the easiest way to go. (I made some tweaks to mine to run it from a plug-in power source, but batteries in a pointer should last a whole evening, so that might not be worth the effort.)

I had two small front surface mirrors (the 'shiny' part of the mirror being on the front of the glass and not behind it-- cheaply had from eBay or Electronic Goldmine, etc.) so I bounce the laser off the first one on to the second. That way the laser doesn't have to be in front of the mirror, but you can do it however fits the best for you. I literally just glued the mirror to the motor with hot glue and glued the motor to some scrap foam. Then I used just a dab of glue to hold the second mirror in place as well as the laser. Lining everything up took a little trial and error, but once it was right I just glued things in to place. Optics engineers will cringe, but it works:



The laser will bounce off the mirrors and draw a circle (or oval, depending on the alignment). The idea is to line that up such that the laser clears the top 'window' and shines on the inside of it, preventing any laser light from escaping from the prop. The laser is low power (5mW) and the mirror is sweeping it quickly (so it's likely "eye-safe" anyway), but better to be safe than sorry.



With the laser running I just held it up to find about the right distance from the back of the tombstone and then cut a piece of foam to the right length. Hot glue again was used to secure the laser vortex part to the 'support' and I held it in place until the glue cooled to assure the proper orientation. If there's anything blocking the vortex I simply melted it away in the foam, and if there was light getting anywhere I didn't want it to go, I used a little black electrical tape to block it.

The foam construction could result in a little vibration depending on the motor for the vortex-- a harder material like wood/metal/plastic could be used instead. The foam in mine seems to be holding up OK though. Once the laser is mounted you can run a little fog/smoke (I just used one of the ~$20, 400W mini-foggers) and see how the vortex looks.



Some matte black paint was used to black out the top of the support holding the laser and the inside of the arched 'window'. Basically if anything was looking too reflective I just hit it with black. The skull itself hides the laser + scanning mirror assembly from view.

To give the piece a little more 'mood' lighting, I used a strip of RGB LEDs and a small LED light controller. eBay again is a good source-- "RGB LED strip" will get you the LEDs (a few dollars for a foot long strip) and another ~$15 or so will get you a controller with a remote control.

The LED strip goes inside the front edge of the window, behind the lip which hides it from any direct line of sight:



The strips are self-adhesive, so it's just peel and stick. They offer waterproof versions; I just used the standard type instead.

Shown again from a wider angle (also, with the laser on) :



The RGB controller is only about 1" x 1.5", so I simply glued it in to place along side the support arm for the laser. The remote control receiver is on a short piece of wire, so I painted that black and let it sit upright so that the remote control can be used to change colors/effects from the front of the prop:



The controller remembers whatever the last color setting and program was (constant on, fading, cycling, strobing, etc.), so once it's set you can turn the entire system on and off from one power strip. Here's purple in action:



In the next part, I'll show how I built the back piece (to 'keep the fog in') and some other loose ends...

[End part 3]

This is so sik!!! I am totally going to do this with an old tv I have! Absolutely mind blowing.

Whoe!!!! Wow I'm getting stoked for Halloween 2012! Can't wait for the rest of your tut! Thanx a lot for sharing!