I too make custom Lego rolling stock that run on my Lionel layout. I call them Leg-o27. I mount plates to Lionel trucks or buy inexpensive chassis and wheels that are for a bobber caboose for smaller items. Also, I am getting ready to use small switcher drive units for some small Lego Diesel engine shells I have built. No clue what to try and do for configuring a steam engine - but will keep thinking on it:-) Update - I figured out a way to get Lego technic bars to act as drive rods for steam locos using small Lionel diesel switcher engines. I plan to post some pictures of my Lego O27 locos (steam and diesel) and a few of my favorite Lego O27 rolling stock.
Update: To date I have built four Lego engines (2 Diesel engines (small Switchers) and 2 Steam Locomotives with Tenders). I used small Lionel switcher engine motors for all of the engines.
