Posted for "William" <wschertz@ispwest.com>:

No question that the 'pour foam' or great stuff sands easier, but it does
NOT dissolve in acetone like the pink or blue styrofoam.  If you use the
pink/blue material, fill it after getting it to rough shape and then sand
the filler. Don't use bondo, it will attack the pink material.

Bill Schertz