tin cans are tin plated steel. They are too thin, and corrugated. I would only use them for wrap-around field points. Too weak for a real broadhead.

the cut out strips method sounds good for quick feild-expediant arrows or maybe even blowgun darts, if made small enough.  they will not hold up to more than one hit before bending probably, but they will work.  at least they will  not shatter like glass arrow tips.  i recently found some sort of old garden rake, something like a shovel, but lots of little triangles along the edge, and i broke them off for use as arrow tips, but i found that i can't sharpen them by hand, i will have to break out the dremel. 
with the cut outs,  you can easily sharpen the tips on a file or even a rock if need be. 

good if you need a quick fix, but not very sturdy.

thanks for posting that info, btw

i love my dremel. I can work masterpieces with that little noisy thing.

I would think that tin cans would make great one time use arrow points. Man when i was little i cut myself trying to open up a can of ravioli. Very sharp edges and being very weak metal, you can sharpen with almost anything you find out in the woods.

Cheap, efficetive, disposable.
I like it!

Better snapping then than when you needed it most

could cut out two tryangles and slit one almost the full thing then slide the first one in the secand and supper glue it.  like those hunting tips.  im thinking it would at least make it more sturdy.  i dont have any tin cans though  

good idea with the double cut

How practical would it be to use something like iron spikes from a railroad? I don´t mean getting your hands on them but supposing you have them and are going to use them in a spear.

I used iron spikes as sling ammo before as well.