This motif wasn't put on net so I didn't have that aspect to consider. This is motif #20 in the 25 Motif Challenge which is based on the vintage publication DMC Library - Tatting - Editions Th. de Dillmont. This is Plate 5, Figure 27.
I tatted the original in DMC Special Cordonnet in size 20, as I have all the ones before. The instructions designated the difference between rings and chains by saying use one shuttle (rings) or two shuttles (chains). When the outer rings were tatted, which actually used the "ball" shuttle, it said to use the left hand shuttle. The large inner rings were tatted 5, long picot, 5, long picot, 5. No measurements were given for the length but the next small inner ring as well as the next large inner ring were joined into the same long picot. You can see it had to be long enough to accommodate a triangle shape. I learned the hard way that when you got to the last large ring, you didn't make another long picot - instead, you join into the existing long picot of the 1st large inner ring. I did so on the other samples but have circled the problem on this one if you make another long picot. Once you've joined to the existing long picot, then you have a space to join the last small ring and it works out nicely. It's just tricky to watch for.
The original instructions started with a chain and then moved on to the large outer ring/large inner ring. I found it awkward to make the final join and especially when I went to two colors - I had an extra end to hide because I don't like to tat over two tails at the same time. I think it makes it noticeably fatter. So in the two color version, I started with the large rings and was able to hide all my ends at the beginning and only had the two tails at the end to sew in.
You can see on the two color version that I made that last large inner ring join correctly to the long picot on the first inner ring. It makes a nice little triangle when all the rings are joined.
These are tatted in Omega size 30 which I think seems more like size 40. It's noticeably smaller than size 20. I tried using Josephine Rings on one of the motifs. Can you tell which one? Hint - they are much smaller than the regular ring of 6 ds. I used 10 half stitches but it was still really tiny so I went back to the regular rings. This would make a very pretty delicate looking open mat. Or a nice small photo frame. You might even be able to join a large decorative button through the tiny outer rings in the center and come up with a large-ish pendant since this thread is so tiny.
Stuff for the imagination, right?