Some ideas for a motorized pinch valve using a geared stepper motor controlled by an arduino. Need to design and print mounting brackets, gearing mechanism, linear actuator, etc. Design parts in (e.g.) Autodesk fusion 360, print on 3D printer.
Another example linear actuator mechanism…
3d printed rack and pinion
NEMA 17 High Torque Stepper Motor 78 oz-in $12.49