MakerBot Print is our newest print-prepration software, which supports native CAD files and STL assemblies,
allows you to interact with all your printers via the Cloud, and many other exciting new features.
Love this design so much I made seven. I ended up adding Velcro command strips to them, so I could make them into flip clips, or attach them to a vest.
I'd also recommend 0 infill but enough top/bottom and wall layers to have the mag front and back solid.
The rounded tab inside the spring cutout is not supposed to be removed. You can route the spring through the upper gap and tuck the loose end from the outside into the lower gap.
Oh... The filament I was using is so crappy when it printed, that piece was deformed and was either falling out or crooked, so I thought it was just a support.