I recently bought one of these for $A20 (July 2018) from K-Mart to play with. I wanted to practice some seam heat-sealing with something available and cheap before I began modifying an expensive hiking pad: http://www.theultralighthiker.com/axl-air-down-pad/ . I had in mind that I would probably be able to make an inflatable pack frame with one of them (You can make at least two as it turns out – more if you buy some extra valves: https://www.diypackraft.com/shop/merchandise/valves/pressure-fit-inflationdeflation-valves/ ). The material is quite heavy, so I wondered whether it would be suitable for a DIY pack raft.
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It looks very similar to this one from Aliexpres for US$14.28 (July 2018) or this one from Amazon for US$24.11. Walmart etc no doubt have them too – a double one might give more material at a lower per square foot cost – and with more options.
Some of you have no doubt noticed my post about this back in 2011 where I reinforced a cheap Intex brand raft with a blue poly tarp. (I have since seen these sold for <$A30). We canoed 2 Grade 2-3 rapids with one all day with no problems at all – only a very slight delamination of the cheap tarp was happening – but it is easily and cheaply replaced (and you can carry a spare).
If you attach it with tarp clips, this will be the work of a minute, and you can even use the tarp for an overnight shelter! http://www.theultralighthiker.com/home-made-pack-raft/ It held up to 4 years stored in a drum in the bush quite well, such that I was able to get it out for a trip in 2015: http://www.theultralighthiker.com/not-quite-alone-in-the-wilderness/ and put it back in the drum again against future need.
After perusing some pack raft making instructions eg here: https://www.diypackraft.com/construction/how-to/v2/ and here: http://blog.hillmap.com/search/label/Homemade%20Packraft and looking at some simplified pack rafts which are available to be purchased eg http://www.theultralighthiker.com/klymit-packraft/ and : https://www.supaiadventuregear.com/ I am definitely of the opinion that the DIY pack raft is a worthwhile project, and that there are simplified designs out there which will work quite well. (PS: I also rather liked this guy’s DIY pack raft catamaran: https://www.diypackraft.com/2018/06/13/tims-pontoon-kayak-version-2/ )
The K-Mart pad is comprised of two sections: an approx 5’ x 2’ pad and a 1’ x 2’ pillow. Both have valves, so you get approx 24 square feet of quite tough fabric for A$20 (July 2018), which compares favorably to the ‘genuine’ heat sealable materials at perhaps US$14 plus delivery per yard (ie 15 square feet).
I admit the ‘exercise’ is mostly about ‘Can you do it?’ rather than ‘What’s the best way to make a pack raft?’ but still, I think you should get a serviceable raft out of perhaps four of these pads which you can pick up today for A$80 total. Geniuses will no doubt make something out of three (or even two!)
You will also need a heat sealing iron (which you would anyway) such as those readily available for aircraft modeling and other hobby activities, eg: https://www.diypackraft.com/construction/tools/ These cost around $20.
Another DIY Pack Raft supplier: https://iron-raft.co.uk/
A couple of cheap pack rafts for these who can’t be bothered making their own:
https://www.supaiadventuregear.com/ eg https://www.supaiadventuregear.com/products/canyon-flatwater-boat-manufacturing-seconds at 24 oz 685 grams