Techniques used in this stitch (British term / American term):

Chain stitch – ch

Treble / Double crochet – tr / dc

Back Post tr /dc – BPtr/dc

Front Post 5 half treble puff stitch / 5 half double crochet puff stitch – FPpuf. st

2tr/dc decrease – 2st dec: work 3 incomplete 3tr/dc, then yarn over and draw through all lops on hook.

Stitch – st

Foundation Chain: Multiples of 15 + 3

Row 1: Skip 3ch, 1tr/dc in each of the next 2ch, * 3ch, skip 4ch, 3tr/dc in next ch, 2ch, 3tr/dc in next ch, 3ch, skip 4ch, 1tr/dc in each of the next 5ch, rep from*, 3ch, skip 4ch, 3tr/dc in next ch, 2ch, 3tr/dc in next ch, 3ch, skip 4ch, 1tr/dc in each of the next 3ch, turn.

Row 2: Make 3ch and work 1tr/dc in 2nd and 3rd tr/dc below, * 3ch, 1tr/dc in each of the next 3tr/dc below, 3ch, 3tr/dc in space of 2ch, 3ch, 1tr/dc in each of the next 3tr/dc below, 3ch, 1tr/dc in each of the next 5tr/dc below; rep from*, 3ch, 1tr/dc in each of the next 3tr/dc below, 3ch, 3tr/dc in space of 2ch, 3ch, 1tr/dc in each of the next 3tr/dc below, 3ch, 1tr/dc in each of the next 2tr/dc below, 1tr/dc in 3rd ch, turn.

Row 3: Make 3ch and work 1tr/dc in 2nd and 3rd tr/dc below, * 1ch, 2st dec over 3tr/dc below, 3ch, 3tr/dc in 1st tr/dc, 3ch, 3tr/dc in 3rd tr/dc, 3ch, 2st dec over next 3tr/dc below, 1ch, 1tr/dc in 1st and 2nd tr/dc below, 1 FPpuf. st over 3rd tr/dc, 1tr/dc in 4th and 5th tr/dc below; rep from*, 1ch, 2st dec over 3tr/dc below, 3ch, 3tr/dc in 1st tr/dc, 3ch, 3tr/dc in 3rd tr/dc, 3ch, 2st dec over next 3tr/dc below, 1ch, 1tr/dc in each of the next 2tr/dc, 1tr/dc in 3rd ch, turn.

Row 4: Make 3ch and work 1tr/dc in 2nd and 3rd tr/dc below, * 3ch, 1tr/dc in each of the next 3tr/dc below, 3ch, 3tr/dc in space of 3ch, 3ch, 1tr/dc in each of the next 3tr/dc below, 3ch, 1tr/dc in 1st and 2nd tr/dc, 1 BPtr/dc over puff.st, 1tr/dc in 3rd and 4th tr/dc; rep from*, 3ch, 1tr/dc in each of the next 3tr/dc below, 3ch, 3tr/dc in space of 3ch, 3ch, 1tr/dc in each of the next 3tr/dc below, 3ch, 1tr/dc in each of the next 2tr/dc below, 1tr/dc in 3rd ch, turn.

Repeat rows 3 – 4 until you have reached your desired length.