How hard would it to make a personal active digitizer for any laptop screen? The only problem I see is in the coding and getting it to talk to your OS as such a driver. The build shood be easy since aren't they nothing more than two (or four) recievers placed on the x and y axis that judge distance between the two recievers to get a point? I lack the coding knowladge and the build one too. I do have some prior modding skills and would love to fit the receivers inside my frame which has about .5cm of space to work with. What I was thinking was using Arduino or Raspberry Pi (since I don't care if that is on the lid of the laptop since that would be out of my viewing range). If we did have to place it on the exterior frame then I would still want to keep it that thin (the recievers) so I could close my lid easily (the thinner the better). This way you could in theory attach it to any frame and then with a little recalibrating you could use it on the new monitor.