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Folks have already started experimenting with Instructable user mikey77′s silicone caulk / cornstarch mixture called “Oogoo.” This heart-shaped ice cube mold was made from the stuff by Briton Greg Tudor, who cast it around a polymer clay positive. A finished ice cube is to lower right.

Greg comments on his difficulties with the stiff consistency of the cornstarch / caulk mixture, which seems like an opportune time to mention a comment on last night’s Oogoo post from W. Aaron Waychoff, who claims to have had success using glycerine as an additive instead of cornstarch. [Thanks, Greg, and Aaron!]


Sean Michael Ragan

I am descended from 5,000 generations of tool-using primates. Also, I went to college and stuff. I write for MAKE, serve as Technical Editor for MAKE magazine, and develop original DIY content for Make: Projects.



  1. says:

    Neat! However, I’d be a little worried about how food safe a silicon mold made from caulk is.

  2. jduffy says:

    Agreed with the food safe-ness. On a totally unrelated note, another way to thin out the mixture is to use a 2 part caulk 2 part cornstart 1 part mineral spirits mix. This one gives it the consistency of dough, and it sets fast and without shrinking. If you’re using it really soon after casting, 2 parts mineral spirits, 1 part caulk, 1 part cornstarch can be poured, dries in about 4 hours, and is REALLY light, but shrinks after a few days.