Standard Size of Large Modular Hexes

I am thinking about commisioning a woodworker to manufacture a large number of wooden hexes for me. If I do, I'd like to get them in a "standard" size, thus allowing me to sell the extras to other designers for their own work.

Unfortunately, Settlers of Catan is the only game that I own which has a modular hex board. The hexes are 3 1/8" across.

Can anyone tell me whether most of the other modular hex games out there use this same size? Or do different manufacturers use different sizes?