Since the mind searches for an easier way, I want to make a flexible rubber widget without having to generate a mould print and then casting.

I propose an ink ( I have no idea what the molecular makeup would be) that goes through the 3D printer and comes out as a hard print of a widget. The widget is then washed and voila, a flexible rubber. No fuss, no mess. Well a little bit of a mess.

Sweet idea, no?
-- wjt, Aug 25 2014

Silicone. Consider the stuff as found in tubes of caulk/sealant. It is liquid enough to be squeezed, but it contains something that keeps it from "hardening" (well, some, not a lot), until the silicone is out of the tube. (I think I once read that that 'something' is acetic acid, basically vinegar, so the silicone de-liquifies as the stuff evaporates.)

To get silicone through the nozzle(s) of a 3D printer might require a much soupier version than found in a caulk/sealant tube. But if the environment of the 3D printer was hot, say 100 Celsius, evaporation and "hardening" should be rapid.
-- Vernon, Aug 25 2014


I wonder if you could make an artificial eggshell material. Contains a calcium solution, which hardens nicely on loss of solute. Remainder of the printed matrix is a flexible substance. Upon soaking in vinegar (or some other weak acid), the calcium is re- dissolved. (I assume you've seen that trick with an egg...)
-- lurch, Aug 25 2014


[Vernon] Hard plastics give the detail. Soupy silicone would lose form on printing.

[lurch] nice, maybe a plastic polymer with calcium bound side groups that take space when printed but then can be dissolved out of the material.

Ideally this idea needs an additive that is removable after printing for the current 3D printed plastics. Less crossing linking should give more flexibility.
-- wjt, Aug 27 2014


[wjt], the droplet size matters. The hard plastics of course harden quickly after melting, and do it faster when the drops are smaller, and the printer environment is cooler. I'm saying that small-enough liquid-silicone drops in a hot environment can experience rapid evaporation, and consequent equivalent rapid hardening (since silicone is notably temperature-resistant).
-- Vernon, Aug 27 2014


You could always just print the mold as normal, then fill it with a castable silicone or similar.
-- MechE, Aug 27 2014


//loss of solute//

loss of solvent, surely?
-- pertinax, Aug 28 2014


Surely... yep, you're right.

Most of the information has precipitated out or evaporated away from that chem class I last took in '83. Or maybe it's the brain it's all supposed to be stored in.
-- lurch, Aug 28 2014



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