We've tried a few different ways of getting the little ones involved in the pumpkin carving over the past few Halloweens. This year's attempt worked the best. We gave dad the pen and paper and the kid the sharp utensils. Oh, no wait. It was the other way around.
The kid, aka pumpkin carving art director, supplied a sketch of his vision and Dad, in this case, executed said vision. Everybody is involved and everybody still has all their fingers. Win-win.
Last year, our 5 year old at the time, drew directly onto the pumpkin. We loved the result but challenging since his drawing didn't necessarily take into account which parts were to be carved out. It definitely worked better to have him draw it out first and give us a chance to do some necessary interpretation.