For pole-mounted signal lights, I use a piece of brass tube painted grey with a brass washer, painted black, soldered to the top for the "target." A piece of brass tube, also painted black, is soldered in the target and holds a red/green (common anode) LED. The ladder is a piece of 1/2" hardward cloth (galvanized mesh) cut to width/length.
You can see one next to Casey Joan on the left:
My other type is a low mount signal. Again I use a brass tube and bi-directional LED. In this case I use a brass fender washer soldered to a short pole. The concrete stand is hydraulic cement cast in a small "Dixie" cup.