Really good stuff! The main mechanic reminded me of a similar one in The Talos Principle; had me scratching my head for a while (in a good way!).
It’d be nice if there was some kind of fast-forward mechanic though; sometimes I needed to spend a decent amount of time just standing and waiting during the larger levels. The box carry was also a bit wonky - perhaps disabling the box collision during the carry would fix this.
Still, this was a great time! I’d love to see an expanded version of this game with more mechanics, could make for a super-deep puzzle game!