I explained to my son what elementary kids used to play with when there weren't electronic games available, like when I was his age. One such toy is a Bamboo Gun, which shoots rolled wet paper balls. It was far less powerful than the Nerf Blasters you can buy today, but it was a fun toy back then.

I created this imitation bamboo gun to show my son how enjoyable it can be. I also took this opportunity to explain the physics behind the toy and how similar principles are applied in hydraulic cylinders, from small products like RC car shocks and soft-close cabinets to larger systems like vehicle hydraulic steering and heavy machinery such as excavators.

This upgraded version includes improvements I learned from at least 10 drafts. Printing an airtight piston on an FDM printer was more challenging than I thought. I experimented with different sizes, materials, orientations, and layer heights. Finally, it's done. I used different types of paper for the bullets. Printer paper worked best, while toilet paper or flyers were too weak—the gun's pressure would break the bullet mid-air.

How to operate:

Just wet about a square inch of scrap printer paper, roll it into a small ball, and push it lightly into the 6mm hole at the end of the blue barrel. Then, extend the yellow piston out with about 1 cm left before disengaging it from the blue barrel. Aim at your paper target (absolutely not to aim at human or animal) and push the piston with a fast 'high five' slap. The paper ball will shoot out quickly with a loud pop. It takes a bit of practice to get the paper ball to the right size and to push the piston at the right speed. The faster you push the piston, the further the paper ball will fly.

Hope you enjoy it and share the fun I had when I was a kid. FYI, it can also be used as a water gun too.