This is a design improvement for UTG's AR-15 brass catcher: http://www.midwayusa.com/product/855937/utg-deluxe-brass-catcher-ar-15-nylon-mesh-black The product works relatively well, better than my 3D printed brass catcher, but with this modification it works flawlessly! I can even run around with it and it still catches every piece of brass because the bag entrance doesn't collapse. It was simple to design, probably took under a half hour, then maybe 10 mins to add the lip and extra edge blends of version 2 (I didn't bother uploading old version). I didn't do any renders because pictures were more useful, and it would probably take just as long to do that as it did to design. I think buying this product and printing my part for it is THE most cost and time effective way to collect your AR-15 spent brass at the time of this writing. For people not familiar with the practice, in order to save your wallet (and the environment!) spent brass cases are collected and then recycled/reused by re-priming, putting gunpowder in it, and seating a new bullet with a press to create a re-manufactured cartridge. This process known as reloading. For very uniform trajectories, it is best to collect and reload all of the same cartridge brand/lot because then you have near-identical combustion chamber sizes which is one less variable to account for in trajectory differencies. This catcher also saves time by not having to bend over and pick up your brass, and can be used for policing steel cases.I printed in PLA because it is more environmentally friendly and I have not yet needed ABS. My only concern is PLA is fairly UV sensitive, so if its outside on a hot day, some part might warp. This has yet to happen. I used: 10% infill 2 shells 250 um layer height HBP @ 60C (for PLA) printed with the chute facing straight up. Just pop it in and strap on the brass catcher and you're ready to go!