Why not get a shovel full of loose, sandy soil and use that for filler? Can't get much cheaper than that. You could even use some clay-ey soil for a mold - punch your fist in, shape to taste, pour in dirty epoxy. Dale's idea of some chopped fiberglass would be a good idea to provide some extra strength.

Ross

: I have a friend who's into rock climbing and is making himself a climbing
: wall in his basement. He has only one 4x8 sheet of plywood on the wall
: with a very few wood blocks for hand-holds, because the purchased holds
: are expensive (~$7 each, and you need quite a few...)

: I have a bit of extra epoxy and was thinking about attempting some holds. Any
: opinions on what would be the best for cheap, bulky filler? The holds
: would be in irregular shapes cast around something like a big hex bolt for
: attaching to the plywood climbing wall. The holds have to be strong enough
: to support a man's weight.

: So should I keep with the standard sawdust? Sand? (it would mimic rock
: nicely)