We have seen a few 3D printed tools like this, and have made our own laser-cut rectangles for the purpose, but we ultimately have found them to be kind of useless because any two pens give different positions for the Home position (as do any two sessions with even the same pen, if you’re using the diagonal position). The idea of the magnetic easels is that they should stay put once positioned, so you shouldn’t need to fuss with it more than once.