I found the pattern background years ago, I can't remember where from, but it was perfect for this.
Please state size preference when ordering.
A2 in size 420 x 594 mm (16.5 x 23.4 in) £80
A3 in size 297 x 420 mm (11.7 x 16.5 in) £50
Created in Illustrator and Photoshop