I want to print a structure that I can embed in a resin and later dissolve. I know that some fancy 3D printing systems have raft materials etc., that can be printed and later removed easily.
Can any one suggest a 3D printing material that can be dissolved in say water or another readily available solvent?
Wash-away filament used for support in PLA printing is typically PVA, which is completely water soluble and may serve your purpose. It is easily 3D printed as the primary filament and attaches well to the build plate.
Many 3D printer filament suppliers will carry this type of support material. It is important to keep it in a sealed bag with desiccant as it will absorb moisture from the air, rendering it useless for printing.
One such resource is MatterHackers which prices a half-kilogram at US$45. The link provides suitably appropriate information:
PVA (Polyvinyl Alcohol) is a water-soluble material that is often used as a support material, but can also be used to print independently. PVA supports are useful for complex designs where removing support material manually is difficult or impossible, but leaving the part in a water bath overnight will completely dissolve this material.
ABS dissolves in acetone. Indeed actone can be used to clean up 3D prints, see What's smoother? Acetone treated PLA or ABS. PLA maybe not somuch as ABS, see the same post.
PLA dissolves in any chlorinated or fluorinated solvent, such as THF or Chloroform - both of which are significantly more hazardous than acetone.
Hence, as always take care when using solvents, see Safety precautions when using acetone
Also, as filaments are often not pure ABS or PLA, due to additives and dyes, etc., then the solvent may not dissolve the 3D printed part completely, and you may be left with a deformed, rubbery residue.