Consider yourself the most awesome parent to walk this earth if you take the time to repurpose cardboard. Teach Me Mommy's ball drop wall game will keep your toddler entertained, and possibly give you enough time to enjoy a few minutes to yourself.
Toddler threading activity with giant cardboard beads. Could be a little project to have them paint the tubes, let them dry, and cut the tubes into smaller lengths (with some help). Add stickers for decoration and even more fine motor practice!
Marble run made out of toilet paper rolls and paper plates. Ok, so this was a rad idea but pretty tough to do with 2 kids. It would have been good with just my 5 year old. The kids got frustrated that it took so long. I ended up finishing it with a Martin