this piston can be made smaller or bigger, and does not need to have cardboard on it. i just put the cardboard on to make it look a little neater. this does require a small motor however you can probably make a hand wheel attachment.
Step 1: The Piston Mechanisim
get two white connectors and two white rods. attach the white connectors to the rods like in picture 1. then get the motor. and attach the two white connectors to the side of the motor like in picture 3 with the white rods angled down. then get a yellow rod with 3 grey spacers and one blue spacer. then push it into the motor with the spacers on the left side as shown in picture 5.
Step 2: The Barrel.
this is the piston barrel. follow the pictures please
Step 3: Putting Most Things Together.
put every thing together following the pictures.
Step 4: The Frame.
you can cut pieces of cardboard to size if you want and cover this piston.
you are done!