This is the current iteration in my quest for the best wye hopper design possible. For those who don't know, you put a hopper on the front of a powerful Nerf springer or air blaster, and it feeds one dart from an angled tube with each shot. The gentle curve, similar to Kane's Tagger Hopper, and the ramp, taken from CaptainSlug's Knifty Wye, make for a hopper that feeds rubber headed darts far better than anything else I've tried. It even feeds full length darts fine, something I don't know of any other hopper doing, though there isn't much point. This works best with nipple tip darts such as ACC and Artifact, though it also works well with Worker and Mengun darts. Elite darts feed fine but they're garbage, and Accustrike and Waffle head darts mostly feed, but they have may too much friction in long barrels.
For the magazine tube, use 1/2" PVC or clear PVC. You need to keep the air from escaping out the top, with either a cap, ball valve, or the best solution is a [bottle flip cap from Daiso], as discovered by Psyk, and also available on eBay. Anything with a 5/8" OD will fit the barrel port, such as 0.509" ID Aluminum, 0.509" ID PETG, 0.500" ID Polycarbonate, 0.527" ID Aluminum, or CPVC. Attach a stub of 1/2" PVC to your blaster, and this will fit over that. The tubes are a nice press fit on my printer, but if the tubes are too tight or loose, you can adjust the scale a few percent in your slicer. You may need to glue the barrels in to get it to be air tight for optimal performance.
If you want to buy or sell this, see my Distributors page