If your looking at getting started in the world of 3D printed weapons, the 3D Printer Buying Guide is a good place to begin!
V2.8 of the SL-9 lower is based off of the third generation V4.8 SL-15 lower. It shares all of the improved geometry of the SL-15, as well as a fully redesigned Glock magazine compatible front end featuring a reliable last round bolt hold open system, 3D printed magazine catch, and 3D printed ejector.
The SL-9 is a fully featured AR-9 lower compatible with most Glock mag compatible AR-9 uppers. The download includes detailed documentation on the printing and assembly process. So if you want to know more, download the files and take a look!
V1.2 of the Super Lower was released July 2022. It is a second generation lower and works quite well. However, the new versions are much improved and are highly recommended. V1.2 is maintained here for the sake of posterity.