My son (8) built this train. The prototype is line S4 of the "Albtal Verkehrs Gesellschaft" (AVG).
About this creation
Ever since I finished my S1 he wanted to build his own "S"-train. I don't know why he chose the S4 to Achern. I showed him pictures of Jason Allemann's close coupling and we put the rubber bands on the roof, so the single coaches could be separated more easily.