What a great idea! I was thinking of getting my 8 year old twins' hair cut into a bob because their hair is thin and long. I think they've only had their hair cut a handful of times in their life. Their hair used to grow very slow, not anymore. In the fall, they had 3 to 4 inches cut off and it's grown in already. I just measured their hair and they can lose more than 10 inches and still have a nice bob cut.
Now, as far as my 9 year old dd, she won't donate her hair. It's her glory! LOL I wouldn't ask her since her hair has a very strange texture from having ectodermal dysplaysia. I've only seen another person with hair like hers and this girl had ED. ED affects the skin, sweat glands, nails, hair and teeth. Dd's teeth have taken the brunt of ED. Depending on the type of ED a person has, they can be bald or have very thin tufts of fine hair all their life. There's a ED foundation that helps provide children affected with ED with wigs and dental work. DD has a thick head of hair that almost touches her rear end. The texture looks almost as if it has been crimped with the finest crimping tool. After it's washed and dried, it looks so perfect like it's not real. So, I would feel really bad if someone got her hair thinking it wasn't real hair. LOL
ETA: Although dd's hair looks different, it is so beautiful!