This joycon strap and grip holder can be used with 4 straps and 2 grips. It is a remix of MaOI's original model which can be found here: https://www.printables.com/model/55448-nintendo-switch-dual-joy-con-grip-and-strap-holder
I've enclosed the outside edges on this model as I found it to work better for holding the joycon grips in place.
The author remixed this model.
I've enclosed the spaces for holding the joycon grips as I found having the sides open to provide inadequate support to keep the joycon grips held snugly in place.