In article .com,
"Polymer Man" wrote:

My point is, without the specialized high pressure equipment used to
process thermoplastics, you're going to have some difficulties casting
this plastic. Uncontrolled shrinkage is the root of the problem.

I wonder if it would be at all feasible (largely depending on how fluid
the stuff is, and thus how good the seals would need to be) to make the
mold as a cylinder/piston arrangement, and either drop it in a shop
press or toss a clamp on it to provide some pressure. Obviously not the
same sort of magnitude as a high pressure injection mold system, but a
good shop press wailing on a small-area cylinder can get some reasonable
pressures going. ie, if the OP is making his mold 4x4 inches (by 2, or
however long - might be less fussy to make a longer block and cut slices
off of it), a mere 20-ton shop press could apply 2500 PSI, if the
plastic didn't all squeeze out past the piston.

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