I know that some models of 3D printers accomplish stuff like that by using multiple materials and filling the "hollow" parts with a compound that washes away with water or some other gentle solvent. Dunno about these homebrew systems, though.
-- Bob
---------
Then the horns kicked in...
...and my shoes began to squeak.
-- Bob
---------
Then the horns kicked in...
...and my shoes began to squeak.