Hi y'all. Getting ready to build a pair of 2 stringers for my twin grandchildren. Can anyone recommend a good string gauge?  I'm thinkin' the kids will probably beat on them pretty hard, at least until I can give them proper playing instructions. Just trying to prevent excess string breakage, but also thinking of tender young fingers. Haven't seen string gauges discussed here, but might have missed it. Thanks, and Happy 2013 to all.