The uses of plastics on a motorcycle are many and diverse. It's a shame that we are infatuated with expensive material like carbon and aluminum, when some well-made plastic would make aftermarket parts and bike customization so much easier and affordable.
The Acerbis Dual Road Handguards are a good example of what you can do with plastic on a streetbike. Good design. Functional purpose. These handguards aren't for racing and they'll fit on most streetbikes. Use them on a sportbike, dual sport or supermoto.