Would this work? Have 3/4" magnetic segments of various lengths. Also, magnetic curves and stop points would be included. They would have to be thin. The board would be metal. All pieces would be painted or anodized for electrical insulation.
And of course, white for the board and black for the segments.
Then one could conjure up a new course in just a few minutes. It sure would be easier than using tape to set up the course. I think this would be very impressive as a great accessory.
When designing these track pieces one has to be careful that the segments are the right size so that they line up well.
One other material to consider would be reusable stickers. There are some stickers that can be placed and replaced without leaving a nasty residue. Something like these or this.
Thanks for the input. Maybe reversing what is magnetic: The white board would be, and the segments would be metal like brass 3/4" shim stock painted black. But I’ve noticed large size magnetic boards are pretty expensive. And an obvious problem would be to stop the segments from getting out of alignment. So, probably the idea is not very realistic.