You should place some triggers under the platform that detect your loss without having to wait for the ball to fall to the very bottom of the map.
I like the workshop planks & nails setting. You might as well add a few (interactive or not) props in the level such as giant hammers/screwdrivers/sawblades.
The HUB world is a pain to navigate, those little stairs leading to the level orbs should be replaced with ramps. The player should also be able to easily identify a level's difficulty from the HUB.