Hi everyone, I found a useful glitch involving the Resizing Gun that may help with accessing powerups faster/optimizing routes. Here is a video example: To perform the glitch, place the large gateway on the wall in a ceiling corner underneath a floor you want to reach. Then pass through the small gateway so that you are Large Ed, and stand inside the gateways but slightly on the large gateway side. Then you need to jump, then quickly press 'C' to close the gateways. Ed will shrink to normal size, but will be partially inside the wall as well. I'm not sure exactly how, but Ed's head being stuck in the ceiling causes him to be pushed up to the floor above. Hopefully this trick can be used to shorten routes elsewhere!
Nice find! Its been long enough since I played this to know right off the bat if this helps, but that's cool at the very least.