These aren't under-track ones, but they're just as invisible once a train is over them. I use simple posts, as shown below - they're Evergreen .100" styrene rod. I brush-paint them yellow, then add a black stripe - it looks sorta railroady...one of those "what the heck does that sign mean?" kind of things that we less-knowledgeable railfans sometimes see when we're trackside. Posts with two stripes denote that the track beyond the one immediately behind the post also has an uncoupling magnet at the same location.
Here's another visible magnet, but in an area with scenery:
Wayne
I've got a number of visual cues. One has a pickup truck parked next to the track. Another has a trackside ditch filled with a little Envirotex "water." A third has a beaver dam.
If I were going to go with a "standard" marking, I think I would use old oil drums or barrels.
It takes an iron man to play with a toy iron horse.
I figure a RR sign adjacent the magnet was what I would use or suggest.
Rio Grande. The Action Road - Focus 1977-1983
One suggestion I have heard is to mark the tie ends with coloured paint to simulate a spill. I have never tried any method, so I don't know.
Dave
In my one yard I have a number of Kadee undertrack magnets, very easy to spot before scenery, now impossible but I measured their location so I know where they are. So the question is, how others have marked them in a yard. I was thinking of a wire with a small red diamond at the top but would like to get other ideas.