In the interest of building levels for the game as fast as possible, I decided to devote some time to making a tool for it. The 2.5 Tile Editor, can place down 3D tiles within a 2D plane, drawing from custom made tile sets.
I've been using this asset to make the tutorial levels:
And for the levels after that:
Since the tile editor was working so well, I figured I might be able to sell it on the Unity assets store, to get some extra income for the game. I also made a tutorial video, which also shows the extend of the asset's abilities:
The asset has been approved, and is now for sale on the asset store!