I notice a few postin's back, there was a discussion on the subject of curtains. I've found that 'Swish' do a corded set, which is metal, and about 36" long. But as it is made to be extendable, it is relatively easy to shorten further if required. The result is lovely, smooth-running curtains. The set retails at around a tenner, so is fairly affordable!. By mounting it on a board you can make it clamp into the top of the frame quite easily. The Swish range is made by Sunflex, whose website is;
www.sunflex.co.uk