Many moons ago I posted to a thread about low-impact camping/product development/etc. I mentioned my use of surplus equipment.
Mention surplus equipment and you'll either conjure up images of a down-at-the-heels Boy Scout troop or of nutjob militia. An argument can be made, however, that re-using old gear that's made to last and last has a salutary effect beyond mere thrift.
I'll admit to vanity and allow as how I simply like the classic looks of old Swiss leather-and-canvas packs, for example, as much as I like their sturdiness. My kid will be exploring the backcountry with packs I bought used.
Surplus or used gear dilutes the impact of the item's manufacture among many users. An argument can be made that a backpack that has gone through at least three users--the soldier/s to whom it was issued, myself and, presumably, the person I give it to after I'm done with it--has no less than a third the impact on resources as each of us getting a new item for ourselves. Same goes for shelters, sleeping bags, metal canteens...darn near everything except undergarments (a guy has to have SOME standards!).
Most of my kit is made from canvas, wool, leather or steel/brass. The metals are recyclable and the fabrics are renewable. I don't know where silnylon comes from so I don't know if it's renewable or not. It doesn't sound like it.
It certainly violates the *letter* of lightweight backpacking, yet it could be said that surplus/used/renewables have a "spirit" that is in keeping with treading lightly in a certain sense.