This pump is a part of Open Source Microbial Bioreactor project.
Bellow is a step-by-step assembling photo-instructions.
For JSCAD code, please see the link in attachments.
Step 2: insert two thumbscrews on one side
Step 3: pull the tubing through to make a loop, insert hex nuts
Step 4: tighten thumb screws
Step 6: assemble and screw in butterfly screws, don't forget about hex nuts
Step 7: close the pump, insert two other hex nuts
Step 8: insert the other two thumb screws and their hex nuts
Step 9: tighten the butterflies
The pump is ready to be connected to a stepper driver!