About the LEGO peristaltic pump
Just saw your post about the LEGO peristaltic pump and questions you had.
The avtual pump unit uses about 5 dollars worth of LEGO bricks and a latex surgical piece of tubing. The inner roller diameters are adjusted by with electrical tape wrapped around the rollers. It takes a little work to get the tubes to lie over the rollers abd you have to hold thm in place sligjtly with electric tape. Once in place it works pretty well. Not sure about the volume i delivers per turn.
The motor pieces used are from the LEGO power functions and you need to produce a high torque on the pump with the gear ratio shown.
let me know if you have any more questions.