There’s a lot of sketches here and some of them weren’t actually used, but they are all present for whatever purpose someone has for them. I intended to build this one from scratch, but found the concept of making an air tight bladder a bit too tricky at the time. So I ended up purchasing a pretty old used BCD and taking the bladder from that. I then modified what I had planned to fit around the existing bladder shape with changes, so it would be more comfortable and modern.
The fabric I chose was a diamond pattern para pack type material from Rockywoods, standard 3/4″ binding tape, and some various nylon webbing. Nylon should be chosen over polyester for scuba gear. Nylon will absorb moisture where polyester won’t, but remains stronger while submerged and is more resistant to mildew and other mold related issues. Plus, I think it feels much nicer than the coarse texture of most poly webbing.
Special care should be taken to the attachment of the shoulder straps to the “back pad” and those straps to the waist band, as this is where all the weight of the tank and gear will be loaded when on land and when donning the kit. Also keep in mind that when the bladder is filled with air, it will expand around your body, so things like the Velcro belly strap need to be separate from the bladder, or it will squeeze you or release under pressure.