For me, layout is the most difficult part. Finding space large enough is actually the most challenging aspect. Then you have to have battens long enough to reach from clew to peak, and a 13ft bendy stick can be hard to come by. Considerations for the tarp material: I like using very light tarp to minimize the weight aloft. The 3.5oz stuff you can buy at any "big box" store works fine. If you are making a Puddle Duck Racer, the best value for your money will be the 12x20 PDRacer Racing Polysail kit from Polysail International. Just let Dave know you are making this sail and have your PDR hull number ready. Start by spreading your tarp out and making your reference point. Everything is measured from there