This paper investigates the creation of aluminium oxide plasma waveguides that are suitable for the guiding of high power femtosecond laser pulses in non-linear laser-plasma interaction experiments. Circular waveguides were micromachined using a femtosecond laser system to ablate in a controlled manner the surface of two aluminium oxide plates. Creating a semi-circular profile in each plate allows a circular capillary channel to be formed. Two waveguides were constructed: each is 4 cm in length but with a different capillary diameter profile. The first waveguide was a linear (straight) waveguide with a constant diameter of 288 μm and the second featured a taper in its diameter from 289 – 232 μm.