My Father in law turned out to have an awesome stash of rusty bits to start with and I'm loving the results!
Take your rusty bits and a piece of fabric that is ready to dye (pre-washed so all the starches are out). Lay the fabric and rusty stuff on a metal surface like a cookie sheet and spray it all with a 50-50 mix of water and vinegar. Then cover the whole thing with a plastic bag and set in a warm spot.
This is a peak at the fabric after a few hours of cooking.
Once you are happy with the color, put the fabric in 4 gallons of water mixed with 1/4 cup of salt to cure the color. I left in there for a few hours, then rinsed out my fabric really well, used a bit of laundry soap on it and hung it to air dry. And here is the result!
It's so interesting and exciting. My brain is leaping and jumping with ways to use this!
And so naturally I had to start up another batch. Can't let all that good rust go to waste.