Modeled this to fit the SBA3 Pistol Brace. This is intended to be used for storage and display only as having this installed in your pistol brace while in use may constitute modifying your brace to be a stock. I would recommend using a filiment that has some impact resistance like ABS, PC, Nylon. PETG is likely to be fine as well.

Update 9/12: Replaced with v2. Model is easier to print now and only requires two bridges of approximately 1 inch in length. Make sure you put face on build plate before you print or it will fail.

Update 11/26: Added a Lipped version. The lip will need to be supported. This model is if you do not want the slip fit of the normal version and want positive retention.