Print flat side down, no supports or brim necessary. If printing in TPU, make sure there's enough bottom layers for the screws to grab. I printed mine 15 bottom, 3 walls, and 3 top layers with 5% infil for good squish.
The author remixed this model.
Slightly larger buttplate for Lyza's retractable stock. Flush with the sides of the retractable stock. Original is about 10mm from outside edges, this one alleviates the issue I had. Also has some geometric texturing on the back face for cool