Undertank Heat Mats - Air Gap? Styrofoam?

[Bogertophis]

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What do people think about something like this silicone heat mat? The raised texture could help hold the UTH against the bottom while still leaving air channels if you trimmed off the outer lip, and it doubles as a protective surface for your table (and this is just the first one I grabbed, there are plenty other textures/size/etc): https://smile.amazon.com/ZLR-Silicon...353311&sr=8-43

If you just want something to support the UTH (keep it against the bottom of the glass tank), one thing I've used in the past is just a scrap piece of folded "hardware cloth" (welded wire mesh). I'm always making my own tank tops- no, not the kind I wear! And then I used a tile underneath it (much cheaper than a fancy silicone mat)- the tile wasn't thick enough to reach up against the UTH, & the "hardware cloth" has tons of air flow.

Setting up a tank, you can really get creative- there's many ways to do things that will work & be safe. I guess that's why if my garage could talk, it would tell you what a "pack-rat" I am. I rarely need to run to the hardware store.