After seeing the marble maze contest, I wanted to print something similar if not better. I found the Modular Marble Drop Blocks were a possibly larger option with plenty of options to mess with. As other mentioned though, some of the taller blocks are noticeably off by sometimes a few mm. This simple fix scales those models height to be rather close to the correct height as well as the half height blocks which were a little off too. Not a perfect fix since these are from the .stl but less than .1mm off should work well enough.