I have decided to try winding lots of individual coils for the electromagnet array. I think that the magnetic force will need to be quite strong to have a good guiding effect. I have some fine enameled wire and one of those 'pin-art' things. I'm going to try winding a fixed length of wire on to each pin and then connect them up like an LED matrix. I think the coils will each need a series diode to work in this manner but would actually like to be able to pull and push the stylus magnet so bi-directional current would be good. Winding all of those pins and keeping track of the wire ends is probably going to send me mad! I actually want the final version to be a much bigger but am testing the theory with this small one.