Really impressive presentation. A fun core concept for a game. And knocking things around with physics was very fun! ... until I had to be careful with a paint cube.
Level 4, which introduces the cube, was definitely more difficult than 5 or 6. And then 7 needed far more finesse than the game allows for. Though I understood perfectly well how to make the heart, threading the needle between the blue and black sections was too difficult for me to manage after several attempts. One wrong move, one little nudge, and a blue square gets overwritten. Plus, unlike the other puzzles, resetting with soap renders the stage incomplete-able since there's no source of blue anywhere. (I know other people have commented on level 7 as well so sorry to be echoing things you're already aware of! I try my hardest to complete every jam game so that I can see all the content they have to offer, so I'm sorry I wasn't able to experience the final two stages.)
There are so many nice little touches, like the employee of the month pictures, or the little turn signals which react to player input. And the customer mouse cursor.
One thing which is a little odd was that I had to click on things in the UI twice. Once to select and then a second time to activate it. Generally I'd expect one click to do the trick. Just an observation, not an issue.