My beardie has been wanting to burrow lately, especially when going to sleep; he's been getting under the newspaper and paper towels I've got in his cage as a temporary substrate. I read up and I know some people have burrowing boxes for their beardies!
Two things:
1) What kind of material would you suggest for a burrowing box and where can I find it at an affordable price?
2) What kind of container do most people use for a burrowing box? All the ones I currently have seem either not deep enough for not wide enough.
They often burrow just to be comfortable. In the wild I believe they burrow under dirt and leaves etc to hide and sleep. You could pick up some fleece to create a blanket or use scraps to create a small pile that he can dig into and burrow under. The fleece is soft, easy to clean in the washer, and it doesn't have loops which can get caught on nails. I have a couple of fleece blankets on top of the tile bottom of my tank for the same reason and it works well.
An all out dig box is used when adult females need to lay eggs. Those are usually made out of a plastic bin and a mix of organic topsoil and wet play sand so it's a consistency that can hold a stable tunnel. Since your dragon is male I don't think this is needed.