That reminds me of one of the "hobo knife" ideas I saw somewhere. Its just a steel can lid folded not quite in half to make kind of a small ulu knife. The better tools you start with the better knife you'll have in the end. But something is always better then nothing.

I've used brick strap, the steel strips lumber and other materials come bound together with, along with tin snips to make very effective, very wicked barbed arrow heads on home made arrows. They pierced very easily through milk jugs at about 10-15 meters.

I've also used cut up aluminum cans to make needles for lacing leather.

Considering the availability of sheet metal a set of tin snips would be a very useful addition to anyone's tool kit. Unfortunately a bit too heavy to carry around everywhere. Along with a small triangular file, there's all kinds of useful tools you could make.

In a real, honest to goodness survival situation, it might be worth it to make improvised tools and use them and keep your better tools in reserve. Every time you take your knife out of its sheath you might lose or damage it. If you can use a can lid or an ammo can to cut up dinner or twine, that keeps your Benchmade or Randall in its sheath.