Hi there,

I need to make some bellows for a 20x16 inch camera I am building (inspiration came from this link ( http://petapixel.com/2013/02/12/buil...amera-by-hand/ )

I am following the guidance in this link ( http://www.instructables.com/id/bell...mera/?ALLSTEPS ) but the measurements here are for a 5x4 camera.

Could anyone advice me on what size card I would need? Apparently I should use black Bristol board but not sure how big I will need to buy it in. Also what type of card is best? I have found some for sale here but there are a number of different types and not sure which to go for. https://www.artistpapers.co.uk/shop/...bristol-boards

Any advice would be much appreciated.
Many thanks,
Brendan