Making battery cover

[magnang]

Has anyone here made their own battery / side covers and can share how to do it? My bike didn't come with them, and I'm using pod filters, I'd like to fabricate or have fabricated something that will hide the battery, but a clean look that fits close to the battery

Here's a couple of covers I've seen and like, just not sure where to start... sheetmetal? fiberglass? Plastic?? get one made??