I think regular soil would introduce foreign pathogens, besides anything rough, sharp, big enough or heavy enough to hold down a female if a tunnel collapsed would be a problem, I was using large grain sand, and my females would very very scratched up, so I now use small grain sand, very minimal damage, also if whatever somebody has in egg laying bin is wet on the bottom, females always lay on the bottom 100% of the time, if the eggs are left more than 2 days the eggs will drown
Well there is a few different statements here.
"I think regular soil would introduce foreign pathogens, besides anything rough, sharp, big enough or heavy enough to hold down a female if a tunnel collapsed would be a problem"
Well you covered that, obviously use small grain sand, like play sand, mixed with Eco earth, and sphag or something.
"also if whatever somebody has in egg laying bin is wet on the bottom, females always lay on the bottom 100% of the time, if the eggs are left more than 2 days the eggs will drown"
False bottom? Egg Cleaners? (Dwarf White Isopods).
I started to type up my big long spiel, but its my Niche. Talking to the wife, about getting into breeding panthers, and If I do its the technique I want to try, so Ill share it when it works

.
But the premise is, Completely Bioactive raised Chameleons, Bio Parents, Bio hatched and raised babies, and sold only to Bio Keepers.