Baby Play Yard
This was one of things ML saw on Pinterest or something and said to herself, "I bet if I showed this to R he could make that". So she did. And I did. Naturally, I couldn't pass up an opportunity to 3D print custom dowel caps with our son's initials, and rings to keep the supports from sliding around.
We also got the chance to use some of the Mario Bros. themed felt hanging toys a good friend sent us.