I should add that I had no idea that extremtextil’s current tpu fabric is different to the lot from 5 years ago, and it was only discovered when testing to find the right temperature for the new tool. In the end I had to abandon that project and write off the money and time spent on it. This was hugely irritating, but even though these were going to be multi-chamber sleeping mats to guard against punctures, a systemic and total failure in winter means possible hypothermia and worse.
If not for this discovery I would have bought the plans off Matt and the fabric off extremtextil, as shipping to the UK from Germany is considerably cheaper than from Canada.
As it is, I’ve bought one kit from Matt and will buy another a bit later. I need to be sure that a hard hit on boulders will leave it floating in one piece, and the extra shipping cost is insignificant compared to the possible consequences.