I wanted a mount for my DJI Pocket 3 that works with a backpack shoulder strap gopro mount I already own, so i made this. Hope it works for you! I recommend putting some felt tape (which i show in the photos) so that your pocket 3 is secure. I purchased this from amazon.
btw, if you liked this - also try my v2 DJI Pocket 3 GoPro mount v2 with cold shoe by Jerich0 - MakerWorld
as well as my new simple stand for the pocket 3 DJI Osmo Pocket 3 stand by Jerich0 - MakerWorld