Yes, and no.

Yes, you can cover the outside of a glass jar or votive holder. Yes, you can put a tea light inside. Use patterned translucent polymer to cover the outside of the glass and the light will shine through, making gorgeous patterns.⁠
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No, you can’t use polymer clay to make a candle holder, by itself. And no, you can’t use polymer-covered glass to hold poured candles. In both cases, the melted wax gets pretty hot, and sustained heat could damage your polymer creation.⁠ So use tea lights to keep the flame and the melted wax contained, away from the polymer.
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And no, you definitely don’t want the flame to get anywhere near the polymer clay. It’s certainly not flameproof. Never use polymer clay in any location that gets hotter than you can hold your hand on.⁠ (Click here for some more general polymer clay safety lessons)

Speaking of candle holders, here’s a nifty trick. Use small glass jars. These mini Oui yogurt glass jars are perfect. ⁠

Another good source, aside from the recycle bin, is thrift stores. Keep your eyes peeled for small votives, vases, or jars. ⁠
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Just apply the polymer clay to the outside of the glass, and bake. No, it won’t hurt the glass, and no, you don’t need any special precautions. (There’s so much ominous warning about this in the polymer world…totally unfounded IMHO. We bake at really low temperatures as ovens go! I’ve never had one shatter.)⁠
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You can apply surface effect, too, such as in the third image which uses a crackle (full tutorial on the crackle effect here!). But let your imagination go wild. Experiment, and most of all…have fun!⁠