This is a remix of the excellent design of Ralf's Perstaltic pump. I printed his pump and built it to his specs, but I found that the small stepper motors would not really run the pump consistently or with enough power.
I decided to modify the pump to accept a Nema 17 stepper. This gives the pump PLENTY of power to push whatever liquid that you're trying to push. I had to beef up the bearing holders a bit. I also added some mounts. There's a single pump mount and a 4 pump mount. (I'm using to add fertilizers to my aquarium, so I use the 4 pump version).
I'm still using the same bearings and screws that Ralf is using, so you can get a list of the required screws and bearings from his thing. There are countersunk holes in the pump base to mount the motor. If you don't use the motor mount, I've included a spacer to use in it's place.
The washer goes in-between the bearing and the bearing holder assembly on both sides. You can also use metal washers, but I found you can adjust the printed ones for a perfect fit.
For the bearing mounts, use an infill of at least 50% - You need the strength. I also used 60% infill for the pump top, base and centre - This ensures that everything will handle the stress. The mounting plate and base you can use as little as you can get away with, but better infill means more strength. The pump housing was printed with 4 shells. The bearing holders and mounting plates with 2 shells. I printed everything at 100 microns, but I think that 200 microns should be ok for everything but the small parts.
You probably won't need support -I was able to print everything without. (I always TRY to design to print without support.
Building the pump
I used a 12V 350mA 28oz-in NEMA 17 stepper motor from Robotshop. Part number RB-Ada-138. This motor has a shaft with a flattened side. I recommend this to keep the bearing mount from slipping.
For the screws and bearings needed, see thing 254956.
You will also need screws for the motor.
I created this from the original files found on thing 254956. I brought them into Sketchup and modified them to work with a NEMA 17 stepper.