thumb splint
thingiverse
You might need to adjust the size of the splint in your slicer. This is for an average sized female hand. Try ~130% for a male hand.
Download Model from thingiverse
With this file you will be able to print thumb splint with your 3D printer. Click on the button and save the file on your computer to work, edit or customize your design. You can also find more 3D designs for printers on thumb splint.