Any time there is a color change noted in the pattern (or, indeed, anywhere you like) you can switch from using double stranded size 10 crochet cotton to a single strand of size 3 or size 5. The bag was designed to use scraps of crochet cotton, so feel free to get creative. The only suggestion is to use one yarn continuously through the mesh portion of the bag, as it is harder to securely weave in ends over the mesh stitches.
Special Stitch Patterns:
dc2tog (decrease): Yo, insert hook in stitch, yo and pull up a loop, yo, pull through 2 loops on hook, yo, insert hook into specified stitch, yo and pull up a loop, yo, pull through 2 loops on hook, yo and pull through all 3 loops on hook.
dc3tog (double decrease): Yo, insert hook in stitch, yo and pull up a loop, yo, pull through 2 loops on hook, yo, insert hook into specified stitch, yo and pull up a loop, yo, pull through 2 loops on hook, yo, insert hook into specified stitch, yo and pull up a loop, yo, pull through 2 loops on hook, yo and pull through all 4 loops on hook.
Note: When working the Motif Pocket, dc2tog and dc3tog are referred to as clusters.
Working a filet crochet chart: Think of each vertical line as one stitch and each block as two stitches. You will always work a dc for a vertical line. A block that is filled in is worked as 1 dc in each of the next 2 stitches. An empty block is worked by chaining two and skipping the next two stitches. To turn, ch 2 (counts as first dc). There's a good tutorial here.
Bag Base
With CC1, ch 87 (counts as ch 85 for foundation chain + ch 2 for first dc).
Follow the filet crochet chart (see Notes, above) to work the bag bottom. When finished, fasten off CC1 and weave in ends.
Begin Sides of Bag
The sides of the bag are worked directly into the edges of the bag bottom. Lay the bag bottom flat and join MC to the top, right corner of the bag bottom through the V of thread on the surface of the top of the stitch (see photo).
Round 1: Ch 3, work 1 dc in the surface of each st across the row as described above, work 2 dc into each ch-2 sp, *rotate work 90 degrees and work 2 dc around each post of the dc along the end of the rows,* rotate work 90 degrees and work 1 dc in each stitch across (see photo), work 2 dc into each ch-2 sp, rep from * to * one more time, sl st in the top of beg ch-3, do not turn.
Round 2: Ch 7 (counts as dc + ch 4), *sk 4 dc, dc in next dc, ch 4,* rep from * to * around. sl st in 3rd ch of beg ch-7, work 2 sl st over the next 2 chains, do not turn.
Place split ring stitch markers around the posts of the dc at the corners of the bag. As you work the following rounds, stop periodically to move the stitch markers up your work.
Rounds 3-29: Ch 7 (counts as dc + ch 4), *dc into ch-4 sp, ch 4,* rep from * to * around, sl st in 3rd ch of beg ch-7, work 2 sl st around the next 2 ch, do not turn.
Round 30: Ch 1, sc in same st, *work 4 sc into next ch-4 sp, sc in next dc,* rep from * to * around, sl st in beg ch-1, turn.
Round 31: Ch 1, sc in each st around, sl st in beg ch-1.
Move stitch markers up to this round.
Fasten off. Weave in all ends.
Motif Pocket
With CC3, ch 4, sl st in first ch to form ring.
Round 1: Ch 1, work 8 sc into ring, sl st in first sc to join round. (8 sc)
Round 2: [Ch 3, work dc2tog in first st] (counts as dc3tog), *ch3, work dc3tog in next st,* rep from * to * 6 more times, ch 3, sl st in top of first cluster (see Notes). (8 clusters)
Round 3: [Ch 3, dc into the first st] (counts as dc2tog), *sk ch-3 sp, work [dc2tog, ch 5, dc2tog] in top of next cluster,* rep from * to * 6 more times, work dc2tog into top of first cluster, ch 5, sl st in top of beg ch-3, sl st in top of next cluster.
Round 4: Ch 7 (counts as dc + ch-4), *sc into next ch-5 sp, ch 4, sk 1 cluster, dc into next cluster, ch 4,* rep from * to * 6 more times, sc into next ch-5 space, ch 4, sl st in 3rd ch of beg ch-7.
Round 5: Ch 1, sc in same st, *ch 4, sk ch-4 sp, work [tr, ch 4, tr] in next sc, ch 4, sk ch-4 sp, sc in next dc, ch 4, sk ch-4 sp, hdc in next sc, ch 4, sk ch-4 sp, sc in next dc,* rep from * to * 3 more times, omit final sc of last rep, with CC1, sl st in first sc.
Round 6: Ch 3, work 4 dc into ch-4 sp, *dc in next tr, work [2 dc, ch 3, 2 dc] into next ch-4 sp, dc in next tr, work 4 dc into next ch-4 sp, dc in next sc, work 4 dc into next ch-4 sp, dc in next hdc, work 4 dc into next ch-4 sp, dc in next sc, work 4 dc into next ch-4 sp,* rep from * to * 2 more times, dc in next tr, work [2 dc, ch 3, 2 dc] into next ch-4 sp, dc in next tr, work 4 dc into next ch-4 sp, dc in next sc, work 4 dc into next ch-4 sp, dc in next hdc, work 4 dc into next ch-4 sp, sl st in top of beg ch-3.
Rounds 7-10: Ch 3, *dc in each dc across to ch-3 sp, work [2 dc, ch 3, 2 dc] into ch-3 sp, rep from * to * 2 more times, dc in each dc across, sl st in 3rd ch of beg ch-3.
Fasten off. Weave in ends.
Straps
Lay the bag flat with front facing. With MC, join thread in the 11th stitch from the marker designating the right corner of the bag, ch 1.
Row 1: Sc in same st as join and in each of next 9 sc, ch 2, turn.
Row 2: Sk first sc, sc in each st across, ch 2, turn.
Row 3: Sk first sc, sc in each st across, sc in ch-2 sp, ch 2, turn.
Repeat Row 3 until strap measures 20 inches. (The straps may not seem long enough at this point, but they will stretch when the bag is full, so err on the size of too short.) Finish with a wrong side row. Do not ch 2 at the end of last row.
Connect the strap: Place end of strap against the 11th-20th stitches from the marker designating the left side of the front of the bag with right sides facing. Work a row of sc through the sc at the top row of the bag and the last row of the strap.
Fasten off. Weave in ends.
Pocket Flap
Lay the bag flat with front side up. Join CC1 in the 4th sc from the inner edge of the right side of the strap.
Row 1: Ch 3 (counts as dc), dc2tog over next 2 sts, dc in each of next 32 sts, dc2tog over next 2 sts, dc in next st, turn.
Rows 2-5: Ch 3 (counts as dc), sk first dc, dc2tog over next 2 sts, dc in each st across to last 3 sts, dc2tog over next 2 sts, dc in next st, turn.
Fasten off. Weave in ends.
Finishing
Attach buttons: Lay pocket flat and find the dc 2 rows above the right tr on the top side of the motif (see photo). Sew a button on the front and back of the pocket by holding them on either side of the post of this double crochet and sewing around the post and into the holes of the button on the other side. Repeat this process above the tr on left.
Attach pocket: Lay the bag flat on a table and adjust it so the mesh spaces are rectangular and not stretched out. Line up the right side of the pocket with the right edge of the pocket flap and pin the pocket to the bag along every other row of the mesh where the edge of the pocket overlaps the dc stitches of the mesh. Repeat on left side. The pocket will be wider than the pocket flap. The pocket needs to be a little baggy so that the bag can be easily folded into it for storage.
Pin the bottom of the pocket along the 15th row of ch-4 spaces down from the top. If necessary, re-pin the sides to evenly distribute any slack along the sides. With CC1, whip stitch along the pocket edges. Along the vertical edges of the pocket, when the edge doesn't match up against a dc in the mesh, then just weave the thread through the pocket until you get to the next dc and resume whip stitching. As you whip stitch along the bottom, you need to accommodate the extra length of the pocket bottom by making two small, equally spaced tucks in the pocket and whip stitching them in place as you work across the bottom. Fasten off. Weave in ends.
To store the bag: Lay the bag on a flat surface with the pocket side down. Fold the sides of the bag over the pocket and fold the handles down. Fold the bottom half of the bag up over the pocket. Pick up the folded bag and push the bottom of the folded bag up and through the opening of the pocket so the pocket inverts over the stack. Fold the flap down and secure with the buttons.
When I was in high school, a push for environmental awareness was sparked by concern over the ozone layer. The US government managed to ban CFCs during this time and recycling programs sprouted up in towns all over the country. And then, well, some other crisis caught the media's attention and it seems like over the last 15 years, the nation took the proverbial "one step back" after its "two steps forward."
Copious amounts of scrap crochet cotton in size 10 (to be used double-stranded throughout), size 3, or size 5. Sample used the following: 
