Lotus will make them in any size you want - I talked to them about getting some 12x15 holders made last year. Don't forget in the US, Richard Ritter (lrg4mat.net), S&S, and Alan Brubaker. The guy who makes Argentum cameras in ┐Czech Republic?/┐Hungary? might also make custom holders for less than Chamonix holders. I think he was selling some 11x14 holders on Ebay not long ago.