Sourgrapes: I'd be interested in plans or more details on your harlequin rack as I may do something similar.
I can offer a few drawings. The first one is an overview of the plan. I made each side of the diamond exactly 14". This makes it a little tight for fitting 16 Burgundy-style bottles. I think 14.5" would be better for that (but, of course, decreases efficiency if you have mostly Bordeaux-style bottles to store). The horizontal spacing between diamonds is the same (due to geometry) as the length of one of the sides, so, 14" in my case. The vertical spacing is, due to geometry, sqrt(3) times longer, so sqrt(3)*14 = 24.248" in my case. (I am not sure why the dimension in my drawing is slightly different -- just a drawing error, I think).
I used 1x8's and used a circular saw to cut slots, halfway across the 1x8, to accommodate the intersection. I set my circular saw at 30 deg., and zipped it just over halfway across the board. I then used a wood chisel to remove the material between the cuts. (I actually made four cuts, instead of just two, so that I could more easily chisel the excess wood out.) Technically, the width of the slots should be exactly 3/4" (the thickness of a 1x board), but I made it 1" to give a little slop for assembly. I was very grateful I had that slop when assembling!
I think if I had to do it over again, I may have used 1x10s, just to make the bottles sit farther back into the hole.
You have some choices regarding how to terminate the pieces, where they touch the outer walls. This bears a little thinking about. The second picture shows a close-up of the intersection, as well as the profile of various pieces of terminating boards. I chose to have the outer walls go through the exact center of the intersection, mostly to make the math easier on where the next board should be located. However, this means you have to make a funny, pointed cut on the end, which results from having a 60 deg. cut intersect a 30 deg cut.
I built an outer frame for the rack, and then assembled the boards within that frame as is shown above. The first boards went together well, but small errors accumulate as you assemble farther, making assembly difficult. I wound up having to trim the ends of some of the boards and open up the slots of some of those boards a bit. After I got the boards assembled, I used a power nailer (16 gauge) to nail the inner boards to the outer frame. I also put a nail through each intersection. After nailing, the rack was stout as could be.
That is everything I can think of for now. Ask me questions if there is anything that isn't clear!
View attachment wine rack overview.pdf
View attachment details of intersection.pdf
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