ARCA rail bag plate with bag. Plate designed for the Helikon-Tex "cube" bag. ARCA clamp from Aliexpress (works great), stainless steel A2 screws and nuts. The filling - such as for a punching bag - unfortunately, tire scraps do not work - they are too bouncy. You have to use sand! The whole thing holds very securely on the rifle rail and is easy to disassemble.

Own project. Material: PETG + ASA