I am supposed to be neutral
Especially because my part is really small compared to what you did.
However - this is a great result and lots of stuff were caught in your images!
As to belt slippage, I was sort of afraid it would be a problem, I should have printed the rims... You can add rings on both sides of the timing pulley, cut from your balsa sheet (and reinforced/soaked with super glue or araldite..
I will try to print a new one for you after next weekend.