similar to a magnet marshal , I created this to test downforce. This is my 3rd prototype. Its running with my code for a STM32 board and runs on a usb power source, so you can plug it into a usb batter pack if you need it portable. I also added screws to the bottom so you can have the downforce match a know scale like a magnet marshal as the pic at the bottom shows. All the non electrical parts are 3d printed and I plan to tweak a few things in my 4th prototype.