I was considering making some similar to my skunk traps, made out of 8 inch PVC. I don't think (famous last words) that a badger could dig out of the PVC as long as the doors were solid.
I'm not sure 8 inch would be big enough but I study some fresh wholes the other day and they are only about 8 inches.
I use to catch badger in dirt whole & flat sets for fox and coyote. I would assume the bait would be the same.
With the fur prices the way they it's a good time for experiencing new things and trying different stuff.