Head-mountable devices can include adjustment mechanisms to achieve optimal alignment of optical components during and/or after assembly thereof within the head-mountable device. The alignment mechanisms can be integrated into the head-mountable device itself. A light projecting display element can be adjustable based on operation of one or more actuators within the head-mountable device (e.g., within an arm) to adjust a position and/or orientation of the light projecting display element relative to the waveguide onto which it projects light. The adjustment mechanisms can adjust the display element during initial assembly and/or be operated by actuators that actively adjust the alignment as needed over time.