This ergonomic foregrip prints well without supports and clamps securely to the firearm without cracking.
Slide it onto a STANAG 4694* rail, then use two 6-32 x 1.25" socket-head screws and two nuts to clamp it down.
In the photos, this is mounted on my daughter‘s KelTec™ CMR30 — a .22 Magnum carbine.
* STANAG 4694 (a NATO standard) and MIL-STD-1913 (the American equivalent) are usually pronounced “Picatinny”. ;-}
The author remixed this model.
The original used 6-32 x 1" screws with no nuts. The creator's update used smaller M3 screws with nuts, and required supports to print.
My remix uses beefier 6-32 x 1.25" screws, flexes a bit more to allow for better clamping, and eliminates the need for supports.