Joe,
I think it would be well worth sharing the app. I know Johm McNamara shared a lot of very useful info regarding the use of electrical sensing of a wire during the earlier pages of this thread. I was inspired by his work to do my tramming with taut wires alignment a couple of weeks ago which proved very sucessful. But the simplicity and low cost of your solution (who hasn't got a laptop these days?) makes it accessible to everyone. I will have to think about how to make the most use of it AFTER I've spent the next couple of weeks tarting my house up to make it more saleable but I suspect another round of alignment could be on the cards in the future thanks to your efforts.

Fitting shims is cheap and easy. Working out WHERE to fit the shims is the trick!

Keep up the good work!

Kit