Well, I wrapped up my 2 experiments today. The mud-dye piece didn't come out the way I thought it would, but I'm not totally disappointed... it has interest, and I may do some more experimenting in that direction. What I had hoped for was more of the 'red-rock' color, but I guess our soil isn't red enough.
Here's the final on the rust-dye experiment:
This is the complete piece
The 2 pictures above are closeups of the rust marks of the top picture. The best marks came from the rebar and the chain, but a subsequent session with metal washers did not make any marks that I can see.
What is interesting is that the pieces of metal had no rust on them when I started last weekend. But now they are rusting nicely. I just need to work on getting a good contact between the fabric and the metal. Also, I have been using muslin, and I think I want to try a fabric that is a little more absorbent, mabe a looser weave. I can see more rust play-dates in my future!