The Balloon Experimental Twin Telescope for Infrared Interferometry (BETTII): Progress Towards High Angular Resolution in the Far-Infrared

The Balloon Experimental Twin Telescope for Infrared Interferometry (BETTII) is an 8-meter baseline far-infrared interferometer to fly on a high altitude balloon. In this paper, we discuss the current status of the project, focusing on the optical and mechanical design elements.