Loo Launchers, the TP Toy Rockets.

Loo Launchers are toy rockets made from old toilet paper rolls or any old cardboard rolls/tubes you have lying around the house. There are a selection of 3D printable nose pieces and engine pieces to mix/match and build your own toy rockets, and then decorate the cardboard tubes to suit!

Note: You may need to scale the pieces slightly to fit your cardboard tubes. Do a test print of 1 piece and see if it fits, then scale to suit. They're designed to fit the common brands of toilet paper roll in Australia, but I assume this differs.