I help cub scouts with Pinewood Derby cars. They've always be 3rd grade or older. I was just contacted by a den leader of 6 Kindergarten age kids.
I think an important part of the experience is doing it yourself and I make a point of having the kids use the power tools: Bandsaw, oscillating sander, stationary belt sander, router table, metal lathe and buffer. I have techniques and jigs to minimize the danger on all of these. I do a lot of practice with the kids and the dads are always close by. I never let the kid proceed unless both kid and dad are comfortable.
With these kids, I would still like to have them do the bandsaw. I have in mind a sort of U-shaped fixture to hold the work that would keep the kids hands well away from the blade. I have an old 12" Craftsman tilting head (bad idea) saw with a very fine 1/4" blade that I keep around mostly for the Derby cars.
Thoughts? The den leader is coming over this evening to strategize.
I know the kids will have fun. I built my own 32' test track. I have the means to do all that rail-rider stuff. But that's for the older kids. With these little ones, We will be happy if they make it to the end.