This is a two circuit pump. It requires the following hardware items;

Silicone tubing (food grade) 3m ID, 4m OD (source Amazon)
m3 x 35 screws - 4
m3 setscrew - 1
m3 x 16 button head screws - 3
3x10x4 bearings - 6
Stepper motor, NEMA 17
Some means to control the stepper, (your choice)

This is the prior version and will give you an idea of how it works.

https://www.reddit.com/r/functionalprint/comments/fqr4np/in_search_of_the_perfect_gin_tonic/