I will have to make some cowl bumps for clearance, and have a question
for
the plastic plane types.  I'll need some foam that is easy to sand to
shape,
and notice that Spruce has "polyurethane foam" that sounds like what I
need.
Is there anything like this that's obtainable locally?  Some sort of
building material, or craft item?  

Thanks,

Rusty (I hate fiberglass)

I've made molds for a number of parts and scoops from urethane that is
inexpensive at your local builders supply.  2" thick urethane insulation
in 4 x 8 sheet.  For larger blocks, cut in pieces, peel off the foil
covering, laminate with spray on adhesive.  It shapes and sands very
easily.  If you take off too much you can glue in another piece and
reshape (or fill with spackle or 5-min mud - drywall filler).  You can
cover the surface with duct tape that will release from the fiberglass,
or I "painted" mine with an epoxy-microballoon slurry, and then painted
with mold release.  After you layup the part don't worry about cutting
it to get it off the mold if that's the only way to get it off.  Easy to
glass it back together.  I usually just layup a few plys, enough to hold
the shape, then get it off the mold, glass it back together, and add
more plys as needed for final strength.  Some epoxy slurry filler - sand
and paint.  You can make any shape you need.

Al (I love fiberglass)