This is a front bag rider designed for a GRS Bifrost Stock.
It mounts to the existing mounting points on the stock.
I've made some changes from the first one I printed, the length had been increased and a hole added so that the sling swivel stud does not need to be removed.
If the truss design is not someones cup of tea the can easily be remoed in the fusion 360 file.
Printed on its front face no supports were required as the radiuses are small enough to bridge neatly.