This repository hosts the code for a Teensy 4.0 board to act as a man-in-the-middle, turning a regular USB Mouse into a pressure-sensitive drawing tablet. There are two components, the main .ino file, and the patches to the Teensy 4.0 USB Driver.
A detailed how-to video, including showing the completed project in action, can be found on YouTube.
The main Arduino sketch is in PressureMouse.ino. The necessary patches to the Teensy 4.0 USB driver are in 0001-Add-pressure-mouse.patch and 0002-Add-regular-mouse-endpoint-to-pressure-mouse.patch, to be applied in that sequence. They are to be applied from the directory your-Arduino-library-location/packages/teensy/hardware/avr/x.y.z/. This patch was originally written and tested when x.y.z was 1.57.2.