Just Google 1.5" roll bar clamps, there are even some that say 38mm !
I've been trying to hold out for some 50mm @chandelierman engine guards, but I'm not sure how long/if he'll ever produce any. He's a perfectionist and has said that he won't produce till he's absolutely satisfied with the design and I don't blame him. We've all come to expect only the best when he attaches his name to something.