saw prop mechanics

Just wanted to share a few things I was able to get ready for this year. The ouija board I did not make as Dave on here did but I built the riser for it. The others are simple props. I had searched many posts and came across some really kool ideas from many of you so I took some ideas and ran...

I purchased the Jigsaw doll from the Saw movie and a tricycle. I am trying to figure out a way to have the tricycle roll forward with a motion activator and to then move in reverse in it's original position. Does anyone know how I would do this and what I would need to purchase and from where...