Quick suggestion: Maybe merge rooms 19 and 20? There doesn't seem to be a 'sandbox' room where you can mess around with silicone quantities and be able to look in the mirror immediately so the next best thing is just running between the two which is kinda annoying, and with the trap needing a certain weight to turn off a laser, having a silicone syphon to help get that exact weight would be nice. So you could merge the two rooms and not really lose anything, while facilitating a post-game sandbox room since that's the last room at the moment anyway.