Summary Sorry, but this thing isn't about British claymation. ;) Rather, this thing is for creating rubber grommits commonly to seal pipes or wires passing through a sealed container. You can also do a plug which is just a grommit with no hole. It is also a test of my "auto units" library, so for many values you can type in most anything you want and it should "do the right thing". Printing You can either print the part directly using flexible filament or create a 3-piece mold for silicone or oogoo. (Don't forget to use a mold release like petroleum jelly) In the picture I used the mold method (stl included). It didn't work too great. I think it didn't admit enough air for straight silicone to cure well. It took well over 48 hours and was still fragile enough to be damaged on extraction. Using oogoo instead would probably work better. (If you aren't familiar with oogoo, here is a good write-up: http://www.instructables.com/id/How-To-Make-Your-Own-Sugru-Substitute/)