Absolutely!
In fact I've seen lots of art on saw blades. I've even seen wall clocks made from saw blades, that have been hand painted. Very Cool!
When it comes to using "rusty old metal", the key is preparation.
I use an industrial strength rust remover. Then I power wash, thoroughly. Then I sand completely.
After I have any loose rust, dust and dirt removed, I clean with paint thinner.
I use a good primer (2 coats). Then after I have finished with the artwork and that has thoroughly dried, I give it 3 coats of gloss lacquer clear coat to protect the surface.
I am not very fast with these and it's a lot of work. I don't want to lose what I have done, the 1st time it rains.
