Train using LEGO Dacta Cities and Transportation Sets
Tape flexible straws to the table or use LEGO tubing for the track.
This idea came from Joe Nagata's LEGO MindStorms Idea Book.
From each of 2 sets build one sub assembly.
Then connect the two motors below with a 2 by 2 plate.
Add the RCX to the top.
Add various other pieces to make the train look as you want.