I have a small amount of experience working with foam for sculpture pieces and now a single pack build.
Now that I’m on my second build, I decided to just what another Alan Hawkins suggested. I went on and bought a StudioCreations Shell. Foam is cool but between the time taken to build and the expense / time taken to finish it properly and make it look good, I decided that the next step in my progression would be to try working with a vacuform shell. Yeah, I’ll eventually work my way up to resin / fiberglass I’m sure but foam, while fun, is just a little more pain in the tuchas than it’s worth. If I’m going to create an original piece, it’s a great medium to work with, especially if you have a hot wire rig like I’ve used in theatre construction projects. For a pack, though, at the end it seemed like more trouble than it was worth. Your cost on a quality foam build can easily run into the same money you’d spend on a vac shell construction. After a point, I was like “How did this foam pack cost so dang much? This was supposed to be a cheap build!”
I will make a couple of suggestions since you’re already in the process: Hot Wire Foam Factory makes a great product called Foam Coat. When you go to an amusement park and see dimensional pieces, chances are they are sculpted from foam and sealed / hardened with Foam Coat (that is to say, when they aren’t made of fiberglass). I sculpted my pack from foam and applied several layers of foam coat. When it dries, it’s totally sandable and gives a similar textural quality to what I’ve seen in some Ghostheads’ hero builds. If you’re at all concerned about the foam coat cracking, you can add a portion of Bounce (a Foam Coat additive) to the mixture. It makes the Foam Coat have a little bit of spring to it so it can handle impact a little better. My son gives his 75% sized pack a workout and the Foam Coat has been great about taking his abuse.
The good part is that these products are formulated for use with foam so you don’t have to worry about incompatible products warping or disintegrating later. You can use it thick (for spackling in any jagged cuts like on the sides of your cyclotron), then thin it down for a couple of thin finishing coats where you can get a smooth, buttery finish like brushed metal.
Foam Coat and Bounce add even more expense to a foam build but they really are cool to work with. If you do any Halloween haunt construction projects, it’s very handy stuff to be familiar with. It makes for very durable set pieces and props. I have heard tell in some haunter forums that Lowe’s sells a product designed for construction which is darn near the same stuff, available in smallish to medium quantities for a better price. Bear in mind that it’s a modified version of concrete you’re working with, so too thick a coat of the stuff adds considerable weight.
And it’s available from a professional prop shop just a few miles from my house, (The Engineer Guy, south of Atlanta) so I can just hop in the car for more if I need it.
Good luck!. The sense of accomplishment I got from my first foam build was awesome, so I do get the appeal. This time around I’m trying the vac route and I think that with the right level of finishing and taking my time, it’ll look great.
