I have used James C Brett Pure Merino and a 4mm crochet hook.
The pattern is a variation on the "Red" Triangle on the Woolfest website. You can use just one colour but I thought it was quite fun with the different coloured bobble. The pattern as you will see is basically just 3 rows and each time you have a Make Bobble row you increase the number of dcs before and after by 2.
ch = chain
dc = double crochet
tr = treble
MB = make bobble (work 4 open tr in same st leaving 5 loops on hook, draw yarn through all 5 loops at once)
2 tr into 1st chain from hook, turn (3 sts)
Row 1: Ch 1, 1 dc in each tr across, 1 dc in top of turning ch, turn
Row 2: Ch 3, tr in 1st tr (inc made), tr in each dc across, 2 tr in top of turning ch (inc made), turn (5 sts)
Row 3: Ch 1, 1 dc, MB, 1 dc, 1 dc in top of turning ch, turn
Rows 4 - 6: Repeat row 2, then repeat Rows 1 and 2 (9 sts)
Row 7: Ch 1, 3 dc, MB, 3 dc, 1 dc in top of turning ch, turn
Rows 8 - 10: Repeat row 2, then repeat Rows 1 and 2 (13 sts)
Repeat Rows 7 to 10 until you do:-
Row 35: Ch 1, 17 dc, MB, 17 dc, 1 dc in top of turning ch, turn
Row 36: Repeat Row 2
Row 37: Repeat Row 1
This is where my triangle has finished but it is up to you on the size you want to make.