I've been into the horizontal zipper look since I saw Andy Torres and others rocking this coat and this blazer last year, but it only occurred to me recently what a simple and exciting DIY opportunity this would be.
You will need:
1 coat, thrifted or otherwise
2 separating zippers (each long enough to go halfway around the coat)
A sewing machine, needle, thread, pins, good fabric scissors
Step 01. Decide where on your coat you want the zipper to go, and cut the coat in half, taking care to cut a straight line.
02. Position the zippers along the top of the bottom half of the coat with the openings toward the ends and the zipper bottoms flesh together at the center of the coat. Pin in place, sandwiching the zippers between the coat's lining and outer shell as shown, folding over a bit of each salvage edge.
03. Sew along pin lines with the machine, leaving the edges to do by hand.
04. Repeat steps 2 and 3 with the other edge of the zippers and the bottom edge of the top half of the coat.
05. Finish the edges by hand, tucking the excess zipper down between the lining and shell.
As you can see, this is a relatively simple way to add a lot a lot of interest to an otherwise unexceptional coat. I hope you have fun making one yourself. Don't forget to send me a link or photo.