[Thomas]

Wow, 4.3 mm carbon, are you sure you need that? Quasi-isotropic carbon has about the same stiffness as aluminium, with 40% weight reduction. I would use 2 mm or 3 mm carbon and make less cut-outs. Of course you need some for servos etc., but the others don't do much for weight saving and might hurt stiffness a lot (if you haven't done FEM on them).

Laser cutting of carbon: Yes, it does work, but you need the right machine and the right settings. Of course it doesn't work with a 120 W engraving laser, you want something in the kW range to evaporate the material instead of slowly melting it. A big problem might be emissions, which can pollute the mirrors (which results in overheating) or contaminate the environment.

Water jet cutting of carbon: Yes, it does work. We have cut 10 mm solid carbon and 5 mm sandwich consisting of 3 mm wood core and 1 mm carbon coverings. Last year, the parts were done in wet lay-up and showed minor delamination after cutting. This year, prepreg material was used with autoclave curing and the cuts are very neat.

Machining of carbon: Yes, it does work, and again, you need the right tools and settings. Carbide tools are not suitable for this, as they're very brittle. The best tools for carbon are CBN, but expensive as well. Steel tools are not suitable because carbon diffuses into the tool, changing the chemical composition.
For drilling holes, HSS tools don't last long, but are cheap. HSCO works last longer, but are more expensive.
For straight cuts, a diamond equipped circular saw is working well.

If you get a lot of fraying, I'd say you're not using the right machine or settings.

For any RC project with small quantities and a budget, I would recommend using a dremel with the cheap cutting blades and some cylindrical sandpaper grinders.

That's all off the top of my head, but it should be correct.

Regards,
Thomas