Instructions:

Rnd 1: Ch 6, join with sl st to form ring. Ch 4, (dc in ring, ch 1) 11 times. Join with sl st in third ch of starting ch 4. (12 ch 1 spaces)

Rnd 2: Ch 3, (2 dc in next ch 1 sp, dc in next dc) 11 times, 2 dc in last ch 1 sp. Join with sl st in top of starting ch 3. (36 dc)

Rnd 3: Ch 1, sc in same st, (ch 3, skip next st, sc in next st) 17 times. Dc in first sc to form final ch 3 sp. (18 ch 3 spaces)

Rnd 4: Ch 3, 3 dc in same sp, (4 dc in next ch 3 sp) 17 times. Join with sl st in top of starting ch 3. (72 dc)

Rnd 5: Ch 3, dc in next 5 st. * Ch 4, sk next st, sc in next st, (ch 4, sk next 2 st, sc in next st) 3 times, ch 4, sk next st, dc in next 6 st. Repeat from * 2 times. Ch 4, sk next st, sc in next st, (ch 4, sk next 2 st, sc in next st) 3 times, ch 1, dc in top of starting ch 3 to form final ch 4 sp. (You should have five ch 4 spaces in each corner and 6 dc per side)

Rnd 6: Ch 1, 3 sc in same ch 4 sp. * Sc in next 6 st, 3 sc in next ch 4 sp,
(ch 4, sc in next ch 4 sp) 3 times, ch 4, 3 sc in next ch 4 sp. Repeat from * 2 times.
Sc in next 6 st, 3 sc in next ch 4 sp, (ch 4, sc in next ch 4 sp) 3 times, ch 1, dc in starting sc to form final ch 4 sp. (You should have four ch 4 spaces in each corner and 12 sc per side)

Rnd 7: Ch 1, 3 sc in same ch 4 sp. * Sc in next 12 st, 3 sc in next ch 4 sp,
(ch 4, sc in next ch 4 sp) 2 times, ch 4, 3 sc in next ch 4 sp. Repeat from * 2 times.
Sc in next 12 st, 3 sc in next ch 4 sp, (ch 4, sc in next ch 4 sp) 2 times,
ch 1, dc in starting sc to form final ch 4 sp. (You should have three ch 4 spaces in each corner and 18 sc per side)

Rnd 8: Ch 1, 3 sc in same ch 4 sp. * Sc in next 18 st, 3 sc in next ch 4 sp,
ch 4, sc in next ch 4 sp, ch 4, 3 sc in next ch 4 sp. Repeat from * 2 times.
Sc in next 18 st, 3 sc in next ch 4 sp, ch 4, sc in next ch 4 sp, ch 1, dc in starting sc to form final ch 4 sp. (You should have two ch 4 spaces in each corner and 24 sc per side)

Rnd 9: Ch 1, 3 sc in same ch 4 sp, * sc in next 24 st, 3 sc in next ch 4 sp, ch 4, 3 sc in next ch 4 sp. Repeat from * 2 times. Sc in next 24 st, 3 sc in next ch 4 sp, ch 4, join with sl st to first sc. (You should have one ch 4 space in each corner and 30 sc per side)

Rnd 10: Ch 3, dc in next 29 sc across, * (3 dc, ch 2, 3 dc) in corner ch 4 sp.
Dc in next 30 sc across. Repeat from * 2 times. (3 dc, ch 2, 3 dc) in corner ch 4 sp. Join with sl st in top of starting ch 3. (You should have 36 dc per side)

Rnd 11: Ch 3, dc in next 32 dc across. * (2 dc, ch 2, 2 dc) in corner ch 2 sp.
Dc in 36 dc across. Repeat from * 2 times. (2 dc, ch 2, 2 dc) in corner ch 2 sp. Dc in next 3 dc. Finish off. (You should have 40 dc per side)

Square will look wavy until smoothed out. Stretching should not be necessary.
Simply place on flat surface and smooth with hands.