My main task was to come up with something knee-length and sleeveless that was made of leather, or at least had that appearance. I also wanted to create the appearance of wearing chain mail beneath this garment, but wasn't interested in wearing actual heavy chain mail.
First stop: thrift store.
Step 1: Secure raw materials
Step 2: Pare down the coat
I started by taking out the lining; I knew once I removed the sleeves, it'd be difficult to keep the lining in place, so I decided to live without it.
Next I took off the sleeves. I used a seam ripper to remove the stitches, leaving the fabric that had made up the seam.
Then I cut the collar from the band. The band is the the strip to which the collar is attached; on some coats, the collar might be attached directly to the body piece, but this one had a band connecting the two. I liked the look of having a small strip around the neck, but without a collar.
Finally, I removed the belt, belt loops, and buttons. Because the coat was faux leather, I took my time to cut only the thread, to avoid damaging the coat itself.