The first photo (P1000960) shows 4 strips of 1/8" walnut, glued together at the end that is away from the saw blade. The clamping block is just a single block of fir held down with the clamp on the right. The saw blade cuts through the clamping block and so the block holds down both the longer stock and the little segments. I use two stop blocks, each held down with its own clamp. That way you can unclamp one (which one depends on whether you want your next group of segments larger or smaller), insert a feeler gauge (photo 2, P1000961), reclamp that block and move the other one snug up to the first one. I find that I can get the SEL to within .001-.005 pretty easily. The stop blocks are cut at the appropriate angle for the segments. I hope this helps.
I also find that taking the "fuzzies" off of the uncut stock with some 320 sandpaper between cuts is beneficial otherwise they prevent getting the SEL exactly right and you can end up with some segments narrower than they should be.