These were not cheap,but I think that the end result is definitely worth it.
Sections of 14cm thick foam,at home,in need of covers.
The biggest section is the seatbase/single bed mattress.The two narrower strips can serve as a seat back,but two of them together form the double bed mattress when the bed is extended.There is one small section as an end rest,but serves as the small extra piece of mattress for the bed extension section.
Bespoke covers were also made by a local Bristol firm.Actually,they could have supplied the foam too,but I was not to know this at the time.
The foam has all been covered in a hard-wearing grey upholstery pattern.