DIY Pump Sack for Cascade Mountain Tech Air Mattress

With this print you can turn any trash bag into a pump sack for your Cascade Mountain Tech air mattress.

Printing directions:

• Print everything 100% infill.  Lower layer heights is better so the threads turn out nicer (I used around 0.1mm).  
• No supports.  Threads are a 60 degree taper but most printers should be able to handle it.  
• For the pump body, specify enough wall layers in the slicer that it won't do any infill except at the thickest part in the middle--this should cut down on print time.  
• You may need a brim depending on how good your bed adhesion is (make sure to remove any sharp bits after removing the brim so it doesn't puncture your bag).  
• I used PLA, but any rigid plastic should work.  

Installation:

Print all three parts.  The lock ring taper mates with the taper on the pump body, and the nut tightens them together.  The bag goes between the lock ring and the pump body.

For best results, stick a piece of duct tape on a flat area of a large plastic bag (cheap, thin duct tape works better than the good stuff).  Put the lock ring in the middle of the tape and trace the inside of the ring.  Take scissors and cut out just inside the line.  You want the hole small enough that you have to thread the pump body into the hole, maybe even stretch the bag/tape a little.  

Thread the pump body through the hole.  Put the lock ring over the bag, tapered side towards the bag.  Install and tighten the nut.  

You can skip the duct tape, but in my experience the bag will tear at the lock ring if the pressure gets too high (this might be OK for sturdier bags).  With the duct tape, the lock ring will not be the failure point.