I liked the creativity of being able to scale walls and scale lava through walls. It works well since the puzzle has few enough scalable items that you can reason about what must be possible. The level design shows a lot more creativity than I would have expected to be possible for the mechanic.
The lava and goal look a bit too similar.
The clickable area for scaling an item is quite small, which made it difficult sometimes to click on an object while it was falling. A pause button would have helped with the timing, or slower gravity, or larger clickable areas, or time being paused while I am resizing any object.
Levels 9-11 were annoying because I figured out the solution but the physics is a bit buggy if I move a slider too quickly and the timing is difficult. I found that I had to move my mouse extremely quickly, but then slow down significantly as soon as the resized object is about to start pushing something.
Levels 12-14 seem to require exploiting the ability to sometimes bug through walls by resizing, but this feels like a physics bug rather than an puzzle solution.