From the great incubator projectmay be similar Im thinking
looks about the right height
Finally another update.. I got a tray built out of acrylic but when I tested it in the incubator, it blocked way too much of the air flow and created serious thermal banding top to bottom.. So I decided to build my trays out of 1/2 inch hardware cloth. I put some shelf liner in the bottom and this seems to be working really well. I have 3 trays built and while it does seem to still block a little of the air flow, it seems to be ok.