[JackWilliam]

I have the task of creating a scale model of a structure for a client.

It is important that the model is light and so we have discussed using foam for some of the larger parts of the structure.
What kind of foams should I consider using and which should I avoid? Where can I buy foam for milling?

Thanks
Jack

[mike-acg]

Jack,

Does it need to be structural as well as light? I can suggest any number of signmaking foams but if you are just looking for volume without structure, I have had good luck using the standard insulation foams (pink or blue).

Mike

[JackWilliam]

It doesn't need to be particularly strong, it will have a supporting component put through it and really it will just be there to demonstrate the shape of the structure. Therefore it cant be a thin sheet, it needs to be a thicker block (unless laminating up sheet foam is possible).

It also needs to be able to hold a painted finish.

[mike-acg]

Jack,

I did a few of these a while back out of 2" pink foam from the big box store. I used that expensive hardcoat but for a model you shouldn't need it. I've done others since then and just painted with latex paint.Attachment 196076
You can glue up bigger pieces with tube caulk made for foam (can't find any out here in the shop to give you the name but you can get it at the hardware store or lumberyard...)

Mike

[awerby]

Try finding some urethane foam. It comes in different densities, but it sounds like a fairly light one should work for your application. Big blocks aren't a problem. You can also buy it as two cans of liquid which you add and mix - it foams up to fill your mold. Making the mold so that it can be sealed shut will enhance the quality of the resulting block. To paint it, you need to coat it with something first. The manufacturers of foam systems should have some coating suggestions for you. Here are some sources:

Precision Board Plus HDU - Coastal Enterprises
FAST CAST Casting Resin Tooling Boards Machineable Plastic Cedar Ridge California

Please note: you can't use this stuff for lost-foam casting. If you burn it, it can kill you. For that, use EPS or beadboard instead.

Andrew Werby
www.computersculpture.com