I have used vinyl carbon fiber looking sheet 'sticker' stock (the kind of vinyl that they make stickers and logos for cars) on some of the smaller plastic pieces on my quad. Honestly looks like a carbon fiber part from 10 feet. Your grandma would call this stuff 'shelf paper' or contact paper, but it is vinyl. I have some in silver and gunmetal grey. And I know it's around here somewhere. I'm sure I have enough to do a pickguard, if you are interested, PM me and we can work something out. I really don't want any $$$$ for it, maybe some kind of trade? PM me and we can discuss it.
Here is a pic of my quad with the 'carbon fiber' side panels. I know the pic is tough to see it in, but look closely.
Between the seat and the motor is the 'C.F.' Where the shutoff for the fuel is. That is the gunmetal grey
on this next pic under and around the headlights is some more....
I got a couple of rolls of this vinyl on Feebay a couple of years ago. Stuff works great. The one toy that I don't have room in my garage is my quad, so some winters it sits out and some winters it goes to my dad's garage. This winter it sat out most of the winter, till I put it in my broken down delivery pickup truck. I just went out and looked at it and tried to peel some of the vinyl up to see if the adhesive is still holding, and it is. I used a hair dryer to warm up the vinyl to get it to stretch around the funny curves.
I mean if you go this route, you will know it isn't real carbon fiber, but I doubt anybody in an audience you would be playing for would notice. Heck I think you'd be able to fool your bandmates if you didn't tell them!!
Usually Carbon Fiber is used as a weight saving material. Some of us just like the look of it!! I'm thinking you aren't after a pickguard for any type of weight savings. In fact I bet a real CF pickguard is within a couple of grams in weight as a regular plastic one.
Hope this helps!!!!