what is he using?

[simpleyork]

just trying to figure out what Jay is using for his enclosure? cement, plaster, or grout . . .?
https://www.youtube.com/watch?v=FZvNN--ZxqQ

[rocknhorse76]

Looks like grout.

[B_Aller]

he's using a sculpting epoxy, hopefully one of the ones formulated for use in animal enclosures. There are several companies that make sculpting epoxy that will be inert when cured making them acceptable for use with animals. Most polymers work by slowly releasing chemicals so those are not recommended for use with animals.
Stylistically, pretty crappy work- needs relief and detail, but hey that's just me being picky.
B