From my turntable project I needed some end stops. To make everything automatic one needs to stop the train when it reaches the end. There are many ways to do this and I choose to make the end stop intelligent by turning the electricity off when it gets hit. Since I use DC current for my track it is directional so I just turn positive or negative off depending on the end stop orientation. So once pressed you can still drive out but not forward. It took some time to get the right printed parts. First I printed it in one go but that did not work at all see the 4 images that I supplied of the 4 prototypes. It took much more time to develop it then I anticipated. Note when using the Cura make sure to make the nozzle size 0.38 otherwise the 0.4 mm details will be lost. NOTE THESE ELECTRONICS MIGHT NOT WORK ON DIGITAL OPERATED TRACKS! I use kicad for my electronic designs. I included the schematics of the electronics as well. There is a positive and negative version. I used a optical interrupter which makes it a little more complicated to build but a simple micro switch takes too much force to operate. One could use reed relays but still you would need to amplify the signal so the overall cost would be comparable. You need to drill a hole to the bottom of you track to install the optical interrupter. And since the PLA is a little transparent to infra red I glued some copper tape on one side of the PLA interrupter part so it is completely dark for the opto interrupter want the train hits the end.