Bladder blanks are "THE" option for the travellers, DIY builders and the ones who don't want to spend a lot money for all the bladders for every kite they have. It's a kind of universal solution, which consists of bladder eg. "bladder blank" and the serie of adhesive, stick-on or self-stick valves.
When needed you stick them to the right position on the bladder blank, to copy your faulty or damaged original bladder. By that the one can use over-sized bladder and stick the valves when needed, having "one-bladder" and on-site solution for more than just one kite!