I have released an Android app to the Google Play Store. It's called Bangkok Train Map. It comes in a Free version with ads along the bottom, and a Paid version costing 99 baht with no ads.
The app is a display-only rendering of the BTS, MRT and ARL train lines in and around Bangkok.
It does not collect any user data. It does not save any user data. It does not provider any user data to anyone.
Please email me at email@example.com if you have any questions.