"Dave Lyon" wrote in message
news:avNCg.84182$FQ1.83676@attbi_s71...


Another ply on the outside will help, but eventually it will get too
heavy.

I'd go the other way. Skin the outside with 1/" wetsuit neoprene.

Really? Don't tease me, I'm an easy target. It's like making fun of
Jerry's
kids (Lewis, not Springer) , it just really should be done.

Anybody know where I can get some camo neoprene for cheap?

A slightly different solution, that may add more weight , but might be
cheaper than the denser foam:
Skin the outside with lauan doorskins. They're pretty cheap, and it should
spread the load so that the paintballs don't ding the foam.
You might consider making another test panel of fiberglass inside, foam
core, and just the doorskin outside, or a lighter-weight fiberglass cloth on
the outside.

From a cost point of view, I suspect that door skin/foam/doorskin sandwich
glued with urethane glue will be cheaper than fiberglass. I don't know what
thickness plywood you were using before, but this should have the stiffness
of 3/4 inch plywood with about a third the weight. A thicker core will
increase the stiffness without affecting the weight very much.

Tim Ward