So you wish you had extra fingers to do more with your hands? The Third Thumb project explores such an idea. It is a 3D printed thumb controlled by your feet. You can use it to hold your phone, pick things up, and do a whole lot more. The prosthetic device is made up of a 3D printed flexible thumb, two servos, and a bowden cable system.
The foot controllers come with pressure sensors, batteries, and Bluetooth. This video from Dani Clode shows the Third Thumb project in action.