Plarnold's New Doctor

Mine are not "real". For the thread I cut the ends off a 3" riser, took photos and then edited them in Photoshop to color in the openings. Plarnolds look to be a manufactured accessory. If I knew how to form and mold plastic I would have created many of those for our layout although I would have made ours in the light gray. They would be perfect to clean up the tops and also they would lock down the tracks with that lip.

Tricky! I had no idea yours were all smoke and mirrors. This looks like a challenge for me to take up. No doubt Plarnold will meanwhile enlighten us.