I've wanted to knit a Pi shawl for a few years now. I've done a baby blanket based on the Pi formula (double your stitches every time you double your rows) but it wasn't lace.
The 10 shawls in 2010 challenge seemed like a good time to make my Pi. I've picked some stitch patterns from my stitch books that work in the round and fit into the stitch counts and row counts of each section. I'm loving working on it!
The yarn is left over from three other projects. I'm using Sweatermaker Lace, Luxury Baby Alpaca Lace and Fiddlesticks Lace. I thought the colours went together well, and together they give me about 1,000 metres. I may come up a little short and need to get some lace weight in a complementary colour for an edging, but at least I will have used up these three lone skeins in my cupboard!