Leaderboard

Artec or Wilkinson are a good place to start as they're not expensive. However, they most likely won't be calibrated for 3 pickup style guitar and you'll need to buy either 2 bridge or 2 neck pickups and sort out the output later. https://www.northwestguitars.co.uk/p90-pickups/

Tune to the chord of your choice (major or minor) and then if you barre anywhere on the neck, you have that mode of chord at a different pitch. For instance, tune your guitar so that it plays an E major (E B E G# B E), then barre at the 3rd fret and you have a G major and so on. Keith Richards is well known for taking off the 6th string and tuning to open G (G B D B D), although you can leave the 6th on and tune it to D. Play a straight barre anywhere, then play a Amin7 shape and then release it; instant Stones and great for slide.