I noticed my 1.8 kg Campo del Cielo used for outreach was getting rusty. I read through these forums to find a way to clean it up. I decided to use mark8888's cleaning procedure (modified a bit) using Calcium, Lime and Rust (CLR), alcohol and automatic transmission fluid.
I first used mineral spirits and a soft toothbrush to remove some sort of sticky lacquer that it was coated in. Next, I repeatedly used the CLR to brush way the rust followed with an alcohol rinse. Next, I baked it in the oven at 200 degrees for 4 hours to dry it out. Finally, it spent the night submerged in the ATF. Total cost was $16.
Probably could have used a few more iterations with the CLR but, it turned out pretty good for a meteorite newbie like me.
Thanks to everyone that has posted cleaning help in this forum!
Before and after photos: