This is a (hacked together) RG 40xxH Grip Case. I am very new at this and basically took the TrimUI Smart Pro grip case (with permission received via DM) by @dildesigns and reshaped the inside to fit the 40xxH.
The original grip case by @dildesigns is here: TRIMUI Smart Pro Grip Case by dildesigns | Download free STL model | Printables.com
This is a very novice effort but it does work well for my purposes.
Please note - out of respect for @dildesign 's original intention, I made mine the same license.
The author marked this model as their own original creation.