Strip material found!!

Please forgive me, I get exited and write all sort of things in this "English" of mine

I found material for bellows' strips!

Earlier, I was talking about "Yeeah it's 0.28mm, yeah it's good, yeah is it too thick" .... bullshit. This polypropylene is 1mm thick.. the sheet's 2.5m3, prizing 16 euros  / m3 so this stuff was, maybe expensive, but I think it is CHEAP.

I'm now really into making bellows that last for LONG time. I don't know how long; is it 5 years, 10, 20, 50 .. ?! No idea. But using polypropylene as strips, it should be resistant for moisture; during years, I believe moisture may cause some damage if paper or paper-related materials are used.. this is only me thinking, of course. So using plastic, that is really elastic, the strips are NOT the weakest part of the bellows. Perhaps the fabric will start to crack in the corners. 

I really cant make this sheet to crack, even hammering it won't do anything, and you can freely bend it, but as I believe, inside the bellows, between 2 layers of fabric, glued together, it MUST be rigid. I can now make the strips thinner, ... previously I planned that their width would be 3 cm, but perhaps it could be 2.. 3cm would mean total thickness of the strips, when bellows are collapsed, simply 30mm + fabrics; and 2 cm would mean 5cm + fabrics, so these are not bad..