I took photos while I was building my spotlights this year, so I made a little tutorial.
Things you will need:
1/2" PVC coupler. 1/2" non-threaded PVC plug. Wing nut and bolt (I used 1/4-20, you would probably be fine with smaller). LEDs of your choice. You will also need the resistors for the LEDs. This depends entirely on the voltage source you are using. I am using 5v power, so for 3.6v LEDs @ 20 milliamps, it needs 82 ohm resistors.
Some type of clear plastic for your lens. This is 10-year non-yellowing Lexan. You could use acrylic (cheaper) or even something like a CD case or heavy clamshell packaging.
Small rings made of 1/2" PVC pipe. You want them as small as possible without losing strength. I think I got them down to a little over 1/4" wide.
Two pieces of metal tubing for cutting out your lenses and LED holders. Copper pipe would be the best thing to use (retains and carries heat well). I bought "set screw couplings" from the electrical conduit area. Lowes sold singles, Home Depot only sold them in bags, but they were under $4 while copper was all $8 or more. If you have copper pipe on hand already then use that. The main thing is that you want the larger tube to cut a disc big enough to cover the end of the PVC coupling, while the smaller one you want to cut a disc that will fit inside the PVC coupling. I used the 3/4" and 1" set screw couplings, since the measurements are what the inner diameter of the pipe will be, not the actual inner diameter of the coupling itself. Bring the PVC coupling with you to make sure your pieces will fit properly.
"Stabilizer Stake" for narrow sprinkler hoses, found in the sprinkler area of Home Depot for about $3/10 stakes. Depending on how tall you grass is, you may need a taller stake. There are some single piece sprinkler stakes in this area that are about $0.70-$1 apiece.
Adhesives. For final seal, you want a waterproof one. I like Goop. If you can find Marine or Sportsmans Goop, it's more UV resistant, but I can only find regular and Plumbing in my area. For quick gluing, I used 5 minute epoxy. Whatever you use, make sure it's paintable. I used silicone "rainproof" sealant, knowing that it wasn't good for painting, on my first try, but not only did the glued areas not paint, but it contaminated the rest of the spotlight. If you use Liquid Nails, make sure you get the paintable type.
Some kind of heat source to heat up your metal tubing. I used a micro blowtorch like this one from Harbor Freight. You could also carefully use a propane torch or maybe even a cheap clothes iron on high. I tried putting the screws in the oven on 450°F when my torch broke, but it didn't work.
You will also need soldering equipment (heat shrink tubing, etc), wire for power (I used speaker wire but if you want to be really "pro" about it you would need black outdoor low voltage lighting cord), pliers, and clamps big enough to squeeze the PVC plug into the coupler, or a bench vise.
Heat the head of the bolt really well, and press it into the center of the PVC coupler. You want it to be hot enough to let the heat do the work. If you have to use the heat and pressure, you may bend the inside of the coupler. If it stops working, pull it off and reheat it if you can (it may stick if it cools off too much). My blowtorch broke while I was making more. The other way to do this is to use a Forstner drill bit just big enough to put the head of the bolt into. For mine, this required a 1/2" bit, and you must make sure not to drill through the wall of the coupling. Using the heat method makes a hex shaped hole that lowers the chance that the bolt can twist and pop out of the epoxy.
Break it back out once it cools (drop it, use pliers, etc), then epoxy it into place. If it's really too difficult to get it back out, epoxy over it instead, but you risk having it pop back off. If the head of the bolt is very smooth, rough it up really good with sandpaper or wirebrush or a file, or it will pop back off the epoxy. Make sure the epoxy is smeared over the edges of the "underside" of the bolt head (facing the threads), not just underneath it. When you get to the part of the tutorial where you glue the lenses on, you can also put more glue over the bolt
Do this part outside! Take the heat source and the tubing you will use to cut out the LED holder discs with. Heat it up really well, then...
Press it down through the plastic to cut out a disc. Use scrap wood underneath. If the plastic sticks to the cutter, you may want to get a big dowel or something to hold the plastic down through the center of the tube while you pull it off.
When my blowtorch broke, I was able to cut discs with a soldering iron and paperclip instead. I used one of the discs I already made to draw a template with a silver sharpie.
Repeat the process with the clear plastic. With the thick Lexan, the metal tube required constant heat to cut through it and was very difficult. A propane torch might do a better job heating up non-copper material. I first did it with multiple reheats, but then did it by keeping the flame on the metal (up away from the plastic!) while pushing it down. Use bigger pliers than this for that method!
Things you will need:

1/2" PVC coupler. 1/2" non-threaded PVC plug. Wing nut and bolt (I used 1/4-20, you would probably be fine with smaller). LEDs of your choice. You will also need the resistors for the LEDs. This depends entirely on the voltage source you are using. I am using 5v power, so for 3.6v LEDs @ 20 milliamps, it needs 82 ohm resistors.

Some type of clear plastic for your lens. This is 10-year non-yellowing Lexan. You could use acrylic (cheaper) or even something like a CD case or heavy clamshell packaging.

Small rings made of 1/2" PVC pipe. You want them as small as possible without losing strength. I think I got them down to a little over 1/4" wide.
Two pieces of metal tubing for cutting out your lenses and LED holders. Copper pipe would be the best thing to use (retains and carries heat well). I bought "set screw couplings" from the electrical conduit area. Lowes sold singles, Home Depot only sold them in bags, but they were under $4 while copper was all $8 or more. If you have copper pipe on hand already then use that. The main thing is that you want the larger tube to cut a disc big enough to cover the end of the PVC coupling, while the smaller one you want to cut a disc that will fit inside the PVC coupling. I used the 3/4" and 1" set screw couplings, since the measurements are what the inner diameter of the pipe will be, not the actual inner diameter of the coupling itself. Bring the PVC coupling with you to make sure your pieces will fit properly.
"Stabilizer Stake" for narrow sprinkler hoses, found in the sprinkler area of Home Depot for about $3/10 stakes. Depending on how tall you grass is, you may need a taller stake. There are some single piece sprinkler stakes in this area that are about $0.70-$1 apiece.
Adhesives. For final seal, you want a waterproof one. I like Goop. If you can find Marine or Sportsmans Goop, it's more UV resistant, but I can only find regular and Plumbing in my area. For quick gluing, I used 5 minute epoxy. Whatever you use, make sure it's paintable. I used silicone "rainproof" sealant, knowing that it wasn't good for painting, on my first try, but not only did the glued areas not paint, but it contaminated the rest of the spotlight. If you use Liquid Nails, make sure you get the paintable type.

Some kind of heat source to heat up your metal tubing. I used a micro blowtorch like this one from Harbor Freight. You could also carefully use a propane torch or maybe even a cheap clothes iron on high. I tried putting the screws in the oven on 450°F when my torch broke, but it didn't work.
You will also need soldering equipment (heat shrink tubing, etc), wire for power (I used speaker wire but if you want to be really "pro" about it you would need black outdoor low voltage lighting cord), pliers, and clamps big enough to squeeze the PVC plug into the coupler, or a bench vise.

Heat the head of the bolt really well, and press it into the center of the PVC coupler. You want it to be hot enough to let the heat do the work. If you have to use the heat and pressure, you may bend the inside of the coupler. If it stops working, pull it off and reheat it if you can (it may stick if it cools off too much). My blowtorch broke while I was making more. The other way to do this is to use a Forstner drill bit just big enough to put the head of the bolt into. For mine, this required a 1/2" bit, and you must make sure not to drill through the wall of the coupling. Using the heat method makes a hex shaped hole that lowers the chance that the bolt can twist and pop out of the epoxy.

Break it back out once it cools (drop it, use pliers, etc), then epoxy it into place. If it's really too difficult to get it back out, epoxy over it instead, but you risk having it pop back off. If the head of the bolt is very smooth, rough it up really good with sandpaper or wirebrush or a file, or it will pop back off the epoxy. Make sure the epoxy is smeared over the edges of the "underside" of the bolt head (facing the threads), not just underneath it. When you get to the part of the tutorial where you glue the lenses on, you can also put more glue over the bolt

Do this part outside! Take the heat source and the tubing you will use to cut out the LED holder discs with. Heat it up really well, then...

Press it down through the plastic to cut out a disc. Use scrap wood underneath. If the plastic sticks to the cutter, you may want to get a big dowel or something to hold the plastic down through the center of the tube while you pull it off.

When my blowtorch broke, I was able to cut discs with a soldering iron and paperclip instead. I used one of the discs I already made to draw a template with a silver sharpie.

Repeat the process with the clear plastic. With the thick Lexan, the metal tube required constant heat to cut through it and was very difficult. A propane torch might do a better job heating up non-copper material. I first did it with multiple reheats, but then did it by keeping the flame on the metal (up away from the plastic!) while pushing it down. Use bigger pliers than this for that method!