My husband and I have good experience under our belts, we have trained all six of our minis to drive. He also designed and built me a custom cart, I'll post a pic of it here....
Love to pick your brain! You have built sleighs as well?
What did you use for your runners, and do you find there is a specific length that drives the best?
Does it make a difference where the center of gravity is, and/or height off the ground?