Finally - after the 3rd try on the main medallion, I got the stitch counts worked out so that the design would lie flat without ruffling at the edges, whew! Then, I tatted small motifs like the center of the large one, to arrange together for a necklace. I'll tat some chains or whatnot in between to hold it all together for the finished necklace, but wanted to show you what I've done so far.
Someone on Facebook brought up the issue of SCMR (self-closing mock ring) and I did have a simple snowflake with a SCMR center that got cut from the Craftsy lesson plan due to time constraints. Wouldn't you know, after looking through all through my piles of tatting and notes, I can't find it! So, I'll have to tat it again. I think I remember how it looked...or something similar.