Sometimes people write to ask me if they can use the DIY Packraft plans and substitute cheaper materials in place of the TPU-coated fabrics sold in the DIY Packraft shop.
The short answer is, “Yes,” though there is a reason why every major packraft manufacturer uses TPU-coated fabrics (even if they refer to it as a “PU” or “polyurethane” coating). Check out the Fabrics page for more on that.
At least one person has successfully made a DIY Packraft using PVC-coated fabric. Another person used a plastic tarp and tape. I, myself, used plastic sheeting to build several prototypes (though I wouldn’t consider them seaworthy).
Before wasting money on a large amount of fabric that might not work, get a small sample of any material you’re considering and test it to make sure it performs the way you expect. Spend a few bucks on a DIY Packraft fabric sample pack so you have something to compare it to that you know will work.
The DIY Packraft plans are not designed for sewing and gluing, so if you want to sew and glue the material you will have to modify the patterns yourself. If you’re not an experienced sewer, I don’t recommend this approach, as I cannot help you.
Note that PU (polyurethane) and TPU (heat-sealable thermoplastic polyurethane) coated fabrics are not the same thing. TPU is sometimes referred to as “polyurethane,” but the reverse is not true. PU-coated fabrics cost much less because the PU coating is usually so thin that it isn’t even waterproof, let alone airtight. PU is not heat sealable. I am not aware of anyone who has successfully made a packraft out of PU-coated fabric, though I know at least one person has tried.
Also, if you buy a can of liquid polyurethane at your local hardware store and paint it onto some fabric, do not expect it to perform like a TPU-coated fabric. Yes, I know that some skin-on-frame boats are made this way; the important difference is that they do not have to fit into a backpack. If you fold and roll fabric that you have painted with polyurethane, even the most flexible PU paint will crack and flake away from the fabric. I have already tried it myself, so don’t waste your time.
In short, you can use the DIY Packraft plans to make a packraft out of anything you want. Just do your research before spending a bunch of money.