Okay, so I had to essentially redo the garbage blocks to add the multi-layer grey garbage. Here's the new sets:
I decided to make all the multi-layer grey blocks their own images because it's a pain in the ass to try actually assembling them by block, unlike the normal-colored garbage. I've also made thicknesses up to 7 (9 ! blocks cleared at once; requires a chain to accomplish). I think that the absolute top would be 10-layers (requiring 12 total and a special setup), but I don't know how many ! panels there would be at any one time. I'll have to ask someone that has knowledge of the game's mechanics.
Thanks for the update! It feels like you get one every so often, or probably when you make a chain / combo. Will have to experiment with that.
Other than this I have no updates its mostly been clean up duty with the codebase finally going to go on ahead and get the makeshift gui library ready to post so others can use it maybe...