Like a forearm attachment to aid in steadying your aim. I don’t have any. Or anything to attach them to since that fateful day on the Limpopo River. :-}
You could fashion one out of a 2x4, but it is cost prohibitive.
I guess they will be coming after my Bullpup Semi Auto Shotgun next. It’s short but sweet.
I remember seeing Lee Van Cleef use his own version of a Pistol Brace in the Movie “For a few Dollars More”. I imagine our current Nazi AG will want to dig him up and charge him.