I’ve always thought of neoprene as being the material of wetsuits. But Geneva from A Pair & A Spare shows that neoprene makes a pretty cool jacket. She also shows how to make it. The fit is boxy so you can make your own pattern by tracing around a jacket that fits you. With no lining and a simple round neck with no collar, it looks like it would sew up quickly. Go to A Pair & A Spare for the tutorial.
[photo from A Pair & A Spare]