I'm sitting here with ONE mitten shell made out of a water resistant snythetic fabric that I have been using since the late 1970's. I lost the other one snow shoeing here in Montana last year and to save my soul I cannot find anything quite like it. It has Sierra Designs Oakland CA on it in large. It is not a mitten, it is made to go over liner gloves while X counrty skiing/snow shoeing. The color is a coyote with a an extra blue layer across the palm/lower fingers of the hand where you grab a pole. There is a piece of elastic across the back of the wrist just right to hold in place. I miss these. Got any right hand ones laying around or could you make them again. Thin gore tex might work. I think these were before gore tex but irrespective, they have been tried and true valuable pieces of equipment for a long time and were still going strong.
Just kidding, sort of. The closest thing is an Oregon Research piece at like 40 bucks that is too complicated and heavy. I wouldn't change a thing maybe use a more modern high tech water repellent but that's about it.