Using a vacuum forming machine, I was able to make candy molds of LEGO men. They turned out very nice, and I'd recommend the project to anybody else. I made this at Techshop Pittsburgh.
Step 1: Create the mold - 1
First, make sure that you turn on your heating element to warm up. Your settings will depend on your machine, but I left it on the default settings, which was a uniform heat, and about 80% power.
Then, you must create a mold layout. With the masking plate down, I laid out all of my mini figs. They will shake around a little bit from the platform going down and up. I might try attaching them to a large, flat lego surface, but you must be careful to not cover the vacuum intake. It worked pretty well without that, though. Keep them away from the edge by about an inch.
Then, lower the tray. Since they are plastic, I lowered it quite a bit to make sure that I didn't melt them.
Step 2: Create the Mold - 2
Next, lift the mask or clamp on the vacuum molder, and put in your PETG. I bought my piece at the Techshop for $2. I had to peel off a protective film on each side of the plastic before putting it in.
!! Do not use a plastic that is toxic!! PETG is a food grade plastic, and it will not poison you when you make chocolates.
Make sure that the clamps are set before moving on.
Step 3: Creating the Mold - 3
Pull the heating tray over the plastic. This will automatically begin the timer, which you could have set before. I experimented with the timer, but in the end I just waited 30 seconds beyond when the plastic rippled and then became still again. I have uploaded a video of what that looks like.
If you wait too little, then the plastic will not be pliable enough, and the mold will not get into the nooks of the pieces. You can still use that piece of plastic as long as you don't have holes in it. Just reset your pieces and start over.
Step 4: Creating the Mold - 4
At this point, simply push the heating tray back and raise the shelf with the mini figs on it into the plastic. The vacuum former will automatically start vacuuming the air out once the tray is fully up.
Give a little bit of time for cooling. If you try to pull it off too quickly, you will warp the plastic. I waited about a minute to be certain.
The mini figs will be stuck in the plastic. Luckily, they will bend, and they come out easily. I used a small stick similar in size to a LEGO man's lance to pry the hip up from the bottom hole in the back of the legs. That worked pretty well. I don't have a picture from that day, but there is a picture to show you where to pry. If you pry from the other side, you could tear through the "heel" of the mini fig, which happened to me one time.
Alligator LEGOs do not come out easily, and the chocolates that you make with them will also not come out easily. This is due to their legs creating undercuts. If you want to use them, I would suggest filling that undercut with something like clay before molding.
The mold is now complete. Wash it with soap and water because there could be anything on that vacuum former, and you're going to eat the next stuff that touches it. :)
Step 5: Making the Chocolate - 1
The rest is pretty simple chocolate stuff, but I didn't know it until this point, so I'll just throw it on the end here.
Buy chocolate supplies from some kind of candy place. I got mine from Make-A-Cake near Pittsburgh, but I'm sure you could get this stuff almost anywhere. The people there were really nice and helpful.
I bought tubes of colored chocolate, which look like icing tubes, in red, blue, and yellow. I also bought regular milk chocolate nubs.
You must soften the chocolate in the tubes. I just used a pot on the stove with warm water, and I did it by feel. Once the whole tube was soft, I just took off the cap and squeezed it into the places that I wanted that chocolate.
I made a double boiler from the same pot and a metal bowl. Then you just have to stir the chunks around until they all melt together. I filled in the backs of the figures with the plain milk chocolate with a spoon.
Step 6: Making the Chocolate - 2
The filled trays go into the freezer for about 10 minutes. Too short of a time, and they'll not solidify, so they will fall apart when you try to pull them out. Too long of a time, and they will freeze to the mold. So, this is just something that you have to keep trying until you get right. The chocolates should just fall out when you flip it over, but you might have to tap the mold a little to get them to drop.
PETG is kinda flexible, but not enough for you to "pop" the chocolates out.
Bam! Now you're done. Give your mini fig chocolates to your friends, and they'll all think that you're super cool.
We also made gummie candy, but you can figure that recipe out with the internet.