Originally Posted by Lovemydd
Not sure if this would work but here it is anyway. Dd4.5 also loves to invent and build. Instead of buying expensive kits, we collected two build-a-bear boxes, other packaging boxes, toilet and kitchen paper roll tubes only, duct tape, and glue. No instructions- just have fun. Dd built a game with an incline in a box and cut a hole and made up a game where you roll the marble, make it roll back after hitting the edge of a box wall and fall into the hole- you win! It was pretty engaging even for adults. Then she built ( this one with my help) a long inclined tube, hid it in the box and you roll marble from one end to collect from another. She even taped a funnel to collect the marbles on the other end so clean up would be easy.
I don't know if my post is even making any sense.

Ditto. My kids do a lot with cardboard tubes and boxes. They often get frustrated with duct tape, so blue painter's tape is our go-to sticky stuff. Plus they can use it on the walls without me throwing a fit.