I want to build up a couple of custom Fiero's. I have a few ideas I want to tryout on a spare Fiero body before I settle on the final renditions. Is there any type of material I can use to add dimension to a body part that can be easily sanded and formed, or even entirely removed if I want to go in a different direction? Does anyone know of any material that could be used? I was thinking expanding foam but I am not aware of its ability to be layered, shaped by knife or sandpaper, or its ability to stick to the surface of the car. Has anyone used expanding foam for this purpose? Also once I decide on a shape I would like to drape fiberglass over it so I am looking for something light.

Any ideas and insight is appreciated.

EDIT:As I am researching this, it seems that the dust from expanding foam can be toxic to your lungs. It can also be transmittted to others from your clothing. Sanding may not be such a good idea unless there is some non-toxic foam. What I am reading came from a few years ago.

[This message has been edited by hcforde (edited 09-16-2013).]

I've done several projects using foam. I have always used sheet foam and then sanded it to shape with coarse sandpaper or a Stanley Sureform rasp with the curved blade. If you search, you will see where others have used expanding foam, either from a can or the two part products made by several manufacturers. I have not had toxic reactions to the dust, but a mask is always a good idea. My mini wide body car has a couple examples of flat foam being shaped and then glassed. The rear spoiler was rough cut, then glued to the body with Gorilla Glue- then shaped and epoxy fiberglassed to the body. Seems solid as the rest of the rear hatch. If you use any foam but urethane (R-Max brand or similar), you will need to use epoxy resin so the foam doesn't melt. If you use urethane foams, then the polyester resin works fine and is less expensive but not as strong and doesn't have the adhesive qualities of epoxy. Good luck on your project.
https://www.fiero.nl/forum/Forum1/HTML/091046.html

See this thread about the use of foam. This is the proper type to use.
https://www.fiero.nl/forum/Forum3/HTML/000138.html

Thanks, I just read your post here, will check out the links you gave. MUCH appreciated!