As the title says, I made a map of the lost railcave/mysidia railcave. There's already information on how to navigate the cave, but I don't think anyone's broken down the map like this. Not that it's very useful, but I wanted to dig around and see if there was anything hidden that I hadn't found before. No such luck, unfortunately, but oh well!
To get to the eevee, one always goes through the door with no rail running toward it. But, to be specific, one follows this path: North East East North West North East South East North
To get to the field readout and TM 100, one always goes through the door marked on each side by a stone. More specifically, one follows This Path: West West North West North East North West South West
Enjoy, don't mind the messy handwriting, I don't have a tablet.