In a very small build as this, it's important that EVERYTHING have an actual function. As such, I would suggest deleting the o-scope tile and replacing it with a 2 hp blank and an Intellijel VCO 1U so that you can have at least one dedicated LFO to use alongside the Maths. I also pulled the headphone preamp and the mono reverb so that you can have a stereo FX processor that does more than just reverb. Other than that, congrats! You managed to create a build that CORRECTLY utilizes the space in a small cab. And this looks like...
ModularGrid Rack