Airfoil extrusions can be found.
I can suggest to you
www.thebackshed.com if you want to try extrusions as blades.
I must caution you, though, those guys don't give much consideration to the structural issues of assembling their blades and have ended up with many failures.
Failures of the kind that any engineer could forsee.
If you choose to use them, you cannot make the rotor as big as you may think you can from the projects posted on their forum, and you should not under build the attachment spar tube that goes up the middle of the blades.
In short: much less forgiving than wood.