Shellstrike Rival 3 Round Shell

Slight remix of a Shellstrike shell [https://www.thingiverse.com/thing:5336281] designed by another user Darman_Skirata's. I recall when I originally downloaded it they didn't have a rival round design capable of holding 3x rival ball rounds. I used blender's carve tool to fix this one up. Smoothed the inside of the shell and rounded up some of the inside edges.