While cleaning up my garage recently, one of the things I’d saved came to my attention. It was a ceramic spoon holder that the end got broken off of. As seen to the right, I sawed the broken end off so that a nice circle was left to sit the soldering iron in.
It appears to be pretty sound thermally, but as with everything on this site, use your own judgement. Also, if you decide to make one, be sure it’s ceramic or another non-flammable material, and take steps to keep from breathing the dust generated.
If you have no idea what a spoon rest is, here’s one that’s intact off of Amazon. I don’t suggest buying one for this purpose, but it makes for a good reuse. Hacks like this are yet another benefit of being married; I would have absolutely no idea these existed otherwise. On the other hand, you could do something similar with an ashtray if you’re naughty and like to smoke.