Got a PbFasion one infront of me you could use the dimensions from to make your own template.
Length - 108cm
Max width (at centre) - 6.5cm
The bottom line of the headband stays straight, but the top line tapers down from the 6.5cm width at the centre to 3.5cm width about 2cm from each tip, the top line then drops down and out steeply to meet each tip.
The padding at the centre is 23.5cm x 4cm, but it could do with being a tad bigger.