AWESOME AWESOME AWESOME JOB. I could not think of a bettery way to spend the day with your son. Keep practicing and then get another plane. I went from a LT40 to an ultra stick 60. I love them both. The ultra stick 60 is a great second plane. The talcum power I never heard of but it souunds good. I put mine ( rubberbands) in a ziplock bag with some cat litter it takes the oil off them.
Here is my first plane I sold it to a buddy and he put floats on it.

Excellent job guys.