I was thinking about a giant spray paint can etch-a-sketch with the two motors.
I'm a bit more practical originated as I would really like someone to develop some handyman helper Robotics.
The one I think about the most is a wall printer. Something that could both paint a wall and later lay down a painted wallpaper pattern or mural.
Or how about a set of wallboard helping hands. Something that takes the weight of the wallboard and responds to your positioning motions. Heck we could include a rotozip controller that would allow you to trim the edges and cut the holes for the boxes.
This could depending on costs be a fruitful and interesting challenge. The thing about construction/Handyman automation is that it is fuzzy. Dimensions are a bit fuzzy as the materials are not exactly stable. Wood has twists and bends, rooms are mostly square not exactly. But that is merely a challenge.