Press z and m for editor 1 - Blocks 2 - Inside geometry 3 - Spikes 4 - 4 long blocks 5 - Special 6 - Speed Portals and more 7 - Slopes and more 8 - New Pits and more
I did nothing, just changed the cube a bit so you can see it in the level. Literally all credit goes to @chikomastr
