Using a soft sided water bottle (ie. Platypus) or a wine bladder would be an easy option. I could sew up something today that would swallow a wine bladder on the chest and a 1L Platypus behind my head to keep it upright. That would be easy, but I'm hoping I can come up with something at a similar weight that is a bit more elegant and quicker to use.
I have quite a bit of time until I need my PFD be ready, as I currently have neither the equipment or skills to safely venture out on a river in mid-January. I don't think I'll be on moving water until March or April.
My hunch is that I could make an inflatable PFD that:
1) Is weight competitive with the lightest options on the market
2) More elegant/simple/easy-to-use than a design incorporating water bottles and wine bladders.
3) Safer than an pure inflatable PFD by using smaller pieces of CCF.
Even if this doesn't work out, I'd have fun trying.
I'm imagining a vest that uses heat sealable fabrics to create multiple air chambers, and with smaller pieces of CCF bonded inside those chambers to both reduce inflation time and increase safety. Using water bottles/bladders that I carry already would be a multi-use strategy, but I'm not convinced it would be significantly lighter due to the zippers required.
My primary concern is the valves. I haven't been able to find a good source for small, light air valves (ie. Therm-a-rest style) that are easy to bond into place. I want a design that will bond in shear (as opposed to peel). For the fabric, I'm thinking of 70D heat sealable nylon from Quest, although there are 30D options out there:
I anticipating using this raft for a wide range of conditions which include backcountry lake fishing, ferrying my wife and I across remote lakes and waterways, and thirdly for trips involving significant amounts of class 2-3 river travel. Ultimately I'd like two paddles. A good river paddle (Werner Shauna?) and then something really light for fishing/lake crossing - perhaps the paddle blades from Alpacka that attach onto hiking poles or your $8 MYOG paddle. I'd love to hear more about your paddle.
"How would you rank: cost, compactness and performance?"
For the flat water paddle, weight is #1, cost is #2 and then compactness and performance just need to meet the minimum standard of 4 pieces and okay performance respectively.
For the river paddle, it's performance, weight, compactness and then cost. I'll save up longer if need be to get the best one eventually.