In terms of heating:

In terms of what you feel safe with:

In terms of cost:

In terms of attractiveness:

Overall commentary:

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Me,

In terms of heating: ground walnut shells

In terms of what you feel safe with: anything since I've tried them all

In terms of cost: paper towels (although, you have to change them so often costs might add up the same as with particle substrates).

In terms of attractiveness: tile? tho i dont particularly like tile overall.

Overall: I say use what you want as long as you're cautious. Currently the bedding for my beardies is ground walnut shells. I don't know why people get so offensive about it and instead try to keep an open mind. Now I don't know if this makes a difference, but I use ground, not crushed walnut shells. I only know of zilla making these. Those are the ones I use. I have grown to love it over the past year. I have also alternated between that and alfalfa meal. Both are good in their own right but are my top 2.

Walnut shells are NOT a good or safe substrate. I used to use it, until I saw the walnut shells showing up in an xray of my female.

There are only two substrates I use now.

On the warm side, I use non adhesive shelf liner. The kind without the holes in it. You can re-use it over and over. Above all it is safe. I recently placed tape over my shelf liner, making it even easier to keep clean.

ONLY on the cool side do I use pre-washed, pre-screened play sand. I buy it at Home Depot. It comes in a large bag, so you don't run out right away, cutting down on the costs.