They are thin wall glass fibre being the 3rd section of a 6 section 1.8m fishing pole bought in a £1 shop!
Maybe not quite as light as carbon but nicely tapered and ever so cheap.
I have used the slightly bigger diam first and second sections in other planes already so technically they cost 33p!
With such low air velocity the effects of drag are significant. At some point the benefit of stators is lost against the drag they produce.
Obviously an area for later experiment.
The build is a rather more conventional at the moment.
Fitting the radio
and aileron servos.
Next bit is harder - mounting the motor.