My second thought was to try electromagnets. I could turn these on only when uncoupling was needed and when off they would not attract my metal wheelsets. Making magnets strong enough proved challenging. I finally "succeeded" with 6 layers 1½" long of #30 gauge magnet wire wrapped on a 2" length of #6-32 bolt stock; using two of these wired in series and mounted on a steel plate to create a horseshoe electromagnet. They worked, provided the tops of the of the magnets contacted the bottoms of the rails (meaing the ties had to be cut away). But they were still not as strong as the rare earth magnets, drew a lot of power (1.1 amps at 12VDC) and got very warm if left on too long. Mounting them was challenging since I already had the track layed and ballasted. I ruined a bit of track by drilling up from under the layout to a diameter of 3/8"! Not fun.