Passio-Pi Playmat is based on the Crocheted PI Shawl by Sarah Golder which in turn is based on the ‘pithy’ directions for a PI shawl by Elizabeth Zimmermann.

Slip knot start (with free end sliding)
Rnd 1: 3 ch + 9 dc (10 sts)
Rnd 2: Inc Rnd 4ch, (1 dc, 1ch) per st. (20sts)
Rnd 3: Plain round. 3ch, Idc in each st, join with sl.st. (20 sts)
Rnd 4: Ch 3, 1 dc in the space between sts, 1 dc in each st., join with a sl st. (40 sts)
Rnd 5: Plain round (40 sts)
Rnd 6: Inc round (80 sts)
Rnd 7: Plain round
etc, etc.
Inc rounds where ever radius at last inc round is doubled.
Single crochet rounds thru the back loop to achieve lines.

This project has been picked up and continued again on Tues 7.4.2015.
20th round: sc, inc by one (ch) every 3rd sc. The mat measures 23” across Ø @ at end of ball of Salsa.
New Yarn: Passioknit “Folkart” Loxton, this yarn will make a decorative edging.
Next round: “sc, ch1, skip 1, sc” repeat to end of round, slip st in beginning ch, ch 1,
All following rounds: “sc, ch1, skip 1, sc” repeat to end of round, slip st in beginning ch, slip st in beginning ch to finish, break yarn and weave in end.
Ta-Duh!!! This mat is gorgeous – even if I say so myself. I like the little purple tufts which stand up on the “Folkart”.
9.4.2015 Completed. Final weight of mat = 300grams.
Diameter of mat = 69cm or 27¼ inches.
Total cost of project was $6…I think I paid $3 for each ball on clearance. Aud.