C & S made a train for MK to ride in. They took a box I came home with from Costco, colored some wheels on the box (see the tiny red dots on the bottom corners?), put a blanket inside, and asked me to let MK ride her train. She is having fun with it.
C pushed MK around the living room and bedrooms while S ran behind yelling "choo choo!" MK did fall a few times when C was a little aggresive in his turns, but she never seemed to mind--she never cried nor fussed--and would smile when we put her back upright and was pushed around again.