The kayak is made from a single sheet of corrugated polypropylene which is commonly used for political and other temporary signs. The material is usually available in 122cm x 244cm (4ft x 8ft) sheets, although different sizes may be available. For a full-size adult kayak, a sheet larger than 122cm x 244cm will be needed unless the adult in question is small.
Corrugated polypropylene has some advantages for making a kayak: it is inexpensive, it is saltwater and solvent resistant, and it is easy to cut. The biggest disadvantage is that most glue will not adhere to polypropylene reliably. It has been reported that some higher temperature, hot-melt glue (like that of a crafting glue gun) may work. Fortunately, no glue is required for this project.
As always, appropriate safety measures should be taken when attempting any project. This one in particular since a simple mistake could confine you to the briny deep...
Where do I obtain corrugated polypropylene?
Some home improvement stores carry it, but most larger print shops will have it. Some trade names include: Coroplast and Corflute.
How much does the kayak weigh?
Less than 4.5kg (10lb)
If I build one of these kayaks, do I have to use boating terminology when I use it?
We recommend recklessly throwing out words like "bow", and "starboard" when in the company of people who know nothing of boating. When in the company of people who regularly boat, make sure to use left, right, front and back, because they really dislike that. If you are not sure, fall back to esoteric nautical terminology like "stunsail", "punting", "sloop", and "sextant", or just make some words up and say them with confidence.
Can I cross the Channel with one of these?
Possibly. Please make a video if you do and remember that you are responsible for everything you do. Also wear a flotation device.
Can I really build one in 45 minutes?
If you are sober and can use basic hand tools and measuring devices, probably less than that.