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> Also needs to not have undercuts, so you can get it out after you
> ram up the mold.
About undercuts with fine sand casting, it can be done, and it is
relatively simple, but you need practice to do it. Basically you have
a multi-part sand mould. The cup and saucer challenge is a good
challenge for a sand caster. You need to make a one piece casting of
a cup, and saucer with a spoon it, it takes a lot of practice to get
Alternatively if you have a CNC machine, and use architectural
polystyrene, as opposed to a rapid prototyping machine, then you
leave the polystyrene model in the sand and it evaporates when the
molten metal hits it. Undercuts, even complex internal voids.
Regards Charles A.