*Disclaimer: I'm not a professioanl programmer, and the proof is in my code. This is provided AS IS, USE AT YOUR OWN RISK.
PURPOSE: I put this together to provide a visual representation of a hollowing tool while hollowing wood turning vessels. How to use: Webcamera is attached to hollowing rig with camera mounted directly over cutter and moves with the cutter. I use a 3D printed shim that is about 1/4" larger than the cutting tip to provide a visual indicator of the wall thickness. With the shim placed on the cutter, I place a white sheet of paper under the hollowing bar and cutter and captue a picture. Then use the mouse to draw a box covering the bar and cutter against the white background. This white area will disappear leaving the bar and cutter.