Thank you Cypher - yes he is cute. I could put more in but decided to leave it that way for now while starting to handle/tame him. Sadly it was necessary to do a fair bit of spot cleaning as it got very stinky. He still digs the odd tunnel
The shelf under the wheel was out of sight when I had more substrate in and he's discovered it now and seems to like it. It's a tricky one - I like the idea of him having lots of substrate and digging tunnels, but there was no way I was ever going to find him to tame him like that plus too much rummaging to get him out is stressful as well. I'll probably add more at a later stage when he's got used to me.