Game is a good concept, and is pretty good, but doesn't have a reverse button, which would be useful in this type of game, though it would ruin the surprise of the game, which is what you can make. The things you can make seem abundant and useful, which is very nice. Another issue I had is when my parts went to the negatives, which didn't allow me to place anything except the exit down. I wasn't sure if that was a feature, but other then that, 4/5.
Thank you, if i decide to extend the game(which i probably will at this point), i do plan to add a couple of quality of life features, including an undo feature, albeit a semi-undo(as in undo with limited uses) as that would keep the game a little more challenging.
And also on your second point, that was not a feature but indeed a bug, already fixed in the post-jam version (PC version)