It's about an inch at the thinnest part there. I did go a bit thinner than last time to try and cut down on as much weight as possible.
My dream is for the moss to spread across the surface of the hebel, which will add another half inch or so.
The tunnels are going to be on the far sides.
Being for smaller ants there should be plenty of room for some twisty bits.
Here it is with some finishing touches. I added an extra little reservoir up on the far side to help moisten the corner.