I did a home build back in 2004 when two line inflatables were pretty much all you could buy on the market. No software back then to design off. As a sailmaker I had access to high quality Dacron and nylon rip-stop for materials (actually it was free off-cuts from customers jobs over-orders). I used one of my old Naish 7 meter two line kites to template off and salvaged the bladders. Re cut the wing tips to allow forward attachments for front lines and rear attachments for rear lines. I had to buy a Carbon tube to drill the center out and run chicken loop and bridle system off. The kite to myself and the guys a kited with flew awesome. I ended up winning some beach race's that were run that season. I did not have much cash back then as a young keen sailor/sailmaker and could not afford new kites every season.
My kite lasted about one summer until the bladder finally gave out to many times. After that it was not worth buying a new bladder to keep her in the air.
I did not ever make another as I estimated about 15-20 hours to complete it and lucky for me I started working for an oil company and can now afford new gear any time I need it. I am still keen to try another couple of kite builds planned off CAD software. I would just like to find some place I can get custom made Bladders? Anyone know?
To fabricate a really good project you will need a fair amount of professional know how, also highly recommend a commercial style Machine that can stitch straight and 3 step zig zag. Also a good quality nylon thread and large wood table or floor for pinning it all out straight.
Its a lot of fun making and flying your own creation, especially when out on the water with your own brand blazing on the wing tips - So many people could not believe that it can be done just in a garage.
If you need performance out of I kite, you really are best to just buy a production model.
Happy building who ever takes it on. Good times