I buy all my flower pot hides at the dollar store, just incase I break them or they are the wrong size. They can ball up pretty small, which is how they like it. I will take a comparison picture for you and post it in a few minutes.
To put the whole in for the entrance, I use a strong spoon and firmly but carefully chip away where I want to put the entrance, It takes about 15 minutes per pot. I also suggest buying an extra pot or two in case you break one. You'll get a good feel for how hard you can hit the pot without cracking it.
You can also buy plastic pots and just cut them with scissors or even plastic bowls![]()