Quoted from John_I:Magnets in pinball machines have always had poles which are in routed holes to be either flush with the playfield to catch the ball or very close to the playfield to effect the ball like in TAF. There is a reason for that. Surely designers have been tinkering with this ever since BK. You will not get it to work without routing without going to a monster magnet and custom power supply. In that case you better be experimenting on a worn playfield because you might be chipping paint topside!
I really don't think this game needs magnets, but your game... You should stick to stock style magnet parts and add some woodworking/routing skills to the Electrical Engineering skills.
Magnetic fields decay exponentially with distance as I recall, so yes I could easily find that there is no other choice but to do some woodworking on a playfield to accommodate a magnet mod. I'd still prefer to avoid it since I'd rather be able to move the mod from one machine to next without drilling playfields. I'll evaluate a couple options that will generate a stronger field so it can be further from the playfield surface. Obviously, I'm not going to spend unlimited funds on my little pet project but I also don't have a BOM to be concerned with like Stern -- where the cheapest/easiest option is clearly to just route out the playfield and reduce the distance between the magnet to the ball. I'm sure I will be playing this out with a piece of plywood, not any of my machines until I'm damn well ready.