A modified version of Chris Larkin's limb mount (https://www.thingiverse.com/thing:3280609).
I changed a few things to better suit my own supplies:
If you have printed the model correctly, you also need two velcro straps (I recommend flexible ones) as well as a 1/4 screw.
Printing this can be a bit awkward, since you definitely want supports (also in the strap holes), but not all the way though, since that is basically impossible to remove. I had pretty good success with the method shown in the last two pictures - basically have a bit of support on the very ends of the hole as well as in the middle, where it is easy to reach and remove from the side.
The author hasn't provided the model origin yet.