In this instructable I will show you how to make a very small and simple piston out of knex. This is lever activated but can be modified to be circular motion activated.
Step 1: The Frame
make what is shown in the pictures. This will be the frame.
Step 2: Make the Piston Part
This will be the piston and lever.
Step 3: Completion
Follow the pictures.
watch in picture 4 for the blue clips.
move the black peice back and forth and the rods will go in and out.