One-handed Xbox Series X|S controller

It works like this:

Two different versions are included. One for left-handed and one for right-handed gamers.

Print the parts in PLA with regular 0.2 mm layer height settings. All parts can be printed without supports. (the A button has a built in support that you must snap off when assembling).
Print the shoe in TPU.

Assemble the thumb-stick mover armature with pieces of raw filament as hinges. Snap the trigger and face button pushers (in the left-handed version) in the mount piece.

You have a choice between the TPU shoe and a leg strap. Attach one of them to the bottom arm with a piece of filament.

The right-handed version has an extension piece for the arrow buttons. This piece is optional. If you decide to use it, attach it to the mount with another piece or raw filament.

To snap the device onto the Xbox controller, open the thumb-stick armature, and slide the mount on, starting from near the front end of the controller. (in the right-handed version, you must undo two of the ball-joints to open up the armature).

Make sure you clip the mount all the way, onto the little lip between the top face of the controller and the back face of controller.

If the mount doesn't stay on the controller well, you can tie a piece of string or a zip tie between the two rectangular loops at the front and back of the mount piece, tying it around the belly of the controller.

You can add a rubber band below the controller, between the loop in the mount piece and the long bottom arm of the thumb-stick armature. This will add a greater centering force to the stick.

You can buy one assembled here https://www.etsy.com/listing/1204829039/one-handed-xbox-series-xs-attachment