Luna only had infertile clutches, but the process is the same. For me, and her, I found play sand (home depot $3 for 50lbs) and coco-fiber (eco-earth and other similar - it comes in "bricks"
was the best combination. I am sure that peat and play sand would be fine, too but I find that coco-fiber is easier to wet all the way thru (you soak the brick according to instructions). I cannot tell you exactly what ration I used, but approx. 50/50. The main considerations are holding a tunnel so it does not collapse on her and remains moist enough for the duration. My suggestion to get the water/substrate ration correct is add water once you have mixed the two, tamp it down as you would a newly potted plant, then pack it with your hand, but not so much that it is impenetrable, then stick your finger, a stick into it all the way down to bottom and see if it holds the tunnel.
As for size of laying tub - it needs to be at LEAST as deep as she is long and preferably deeper. It should also be wide enough for her to choose where she wants to begin digging rather than being confined to a narrow area. There is an article on chamnews you might want to read, too.
here are some pics and a link to the article



nesting site
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Chameleon Help & Resource Info
0.1 Veiled Chameleon - Luna. She's now hanging from her big jungle gym in the sky
1.0 Beardie - Darwin
0.2 felines - Kyndra and Lita
0.1 African Clawed Frog - Skipper
0.3 Mad. Hissers (2 died ;(
0.1 Chilean Rose Hair Tarantula - Rosa Leigh
0.1 Goliath Bird-Eater Tarantula - Natasha