The fact that failure means completely restarting, as well as the fact that you aren't refunded for misplaced parts, means that if you're stuck on a level you'll have to rebuild nearly identical machines again and again. Plus, some direction-specific parts, like the joiner, can't be flipped, which means that you're limited in how you can orient your machine. Despite these annoyances, I still had a decently good time with the Magic Poo Machine.