Mark Rollins - Model Railroading Posted by dapj20 on Nov 14, 2015 in RailroadMark Rollins - Model Railroading - model railroad information, complete with model railroad circuit diagrams. Electrical Circuits you can make! With 3D wiring Sketches, easy for the beginner. I enjoy model railroading - HO scale thank you. I… more »Send feedback »