I'm not planning to do a ton of support on this; but here are the files for my 3d printed version of Captain Slug's Durendal homemade ranbow-catch blaster. This catch puts the load onto screws or other hardware and keeps the printed parts in pure shear or compression for maximum strength even with poor print quality or low infill percentage. The plunger head is an extremely simple design that, likewise, removes the load from the printed part as much as possible.
Also required are US-spec 1-1/4" Schedule 40 PVC pipe, orings, springs, a plunger rod, fender washer, screws, and barrel nuts. See the Nerfhaven thread or Captain Slug's original machined version for more information and support.
The catch prints as one piece and should be easily adapted to many blaster types, however, it requires you to machine or otherwise assemble your own plunger rod. I have included the .STEP file for the catch and drill guide for openness and easy adaptation. The grips and PH are not included as step files because the PH was drawn in sketchup and the grips are a mess.