All around great game and surprisingly challenging!
I know it would be a lot more technically challenging, but I'd rather see some rudimentary climbing ledge grab / pull up mechanic than the floaty jumping. By the end when you're about a foot tall you can still jump like a foot in the air and it feels really floaty, but I know that's because it would be impossible to cross the chair islands you set up ahead of time without some forgiving jump room. A good example is that if you continue after reaching minimum size, the sink walls tower over you, but you can hop out no problem. I also found it sometimes difficult to select the right drawer for pulling out between middle and bottom before I got really small - no crouch button to lower perspective.
Would love to see the idea developed more. It'd be particularly neat if winning involved hopping into the completed solution beaker like a bath.