my wife and I took our 9 and 10 year old daughters on the JMT this summer and needed rain mitts for them. My wife and I use ZPacks rain mitts and we contacted Joe to see whether he would make special mitts for our girls. He was willing to try. We sent him a piece of paper where we traced the hands of our daughters with a pen and he made special rain mitts for them from that drawing. He made them roomy, so the girls could wear liner gloves inside, but made sure that they are not too big for their tiny hands and thumbs.
It rained a lot on the JMT this summer and our girls were very happy to have their rain mitts.