Hmmmmm......Interesting.
I started out in casting as a teenager helping my father (a Geology Lecturer) imbed mineral specimens in acrylic for student use.
What we used to do was:
1. clean mineral to be imbedded (duh)
2. Get a used, clean milk container (paper type) and fill with clear acrylic resin to about 1"
3. Wait for resin to cure
4. Place specimen into milk container ontop of cured resin
5. Pour resin onto cured resin in milk container (not onto specimen) using the smallest amount
of catalyst possible.
6. Tap milk container to release air bubbles.
7. Wait to cure.
8. Rip milk container away from cured resin
9. with increasing fineness of sandpaper, start sanding the cured resin, finishing all sizes with
1200grit wet and dry.
The problems of this method were:
1. Milk container is an uneven shape inside, requiring LOTS of sanding or cutting surfaces first
with a diamond saw.
2. Acrylic resin can get really hot! and even fracture if too much catalyst is used.
3. Slow.
4. Trapped airbubbles.
5. Acrylic can shatter when dropped from table height!
What would I do to improve this method?
1. Use a clear polyurethane resin. It does get comfortably warm, but not hot enough to cook human
skin.
2. Use the correct surfactant for the clear polyurethane to help remove bubbles (This surfactant can
make a huge difference, even with normal polyurethane resins)
3. Make a mould from silicone
4. Vacuum degas polyurethane prior to pouring
5. fill mould to that 1" level and allow to set under high pressure (60+ PSI)
6. Insert Specimen and cover with degassed (vacuumed) resin.
7. Pressure (60+ PSI) to cure.
The big problems are that you may not have access to vacuum and pressure casting rig, and that the bug you want imbedded may not do oo well under pressure(?)
I have experimented with clear polyurethanes in the past and without using the surfactant, vacuum and pressure, the resin is filled with tens of thousands of airbubbles and would be useless for any sort of display purposes.