The High-Energy Light Isotope eXperiment (HELIX), is a new balloon-borne 1 Tesla magnet spectrometer to measure light isotopic abundances including $^{10}$Be and $^9$Be to energies of ~3GeV/nuc. This requires precise measurements of the rigidity and velocity of the detected particles, necessitating a multi-system detector. The detectors include a magnet/particle tracker for measuring the rigidity, and both time-of-flight and ring imaging Cherenkov (RICH) detectors for measuring the particle velocity and charge. The energy range of interest, high altitude environment, and proximity to the magnet present a challenging environment for a RICH detector. HELIX uses a proximity-focused RICH with an aerogel radiator above a 1m$^2$ focal plane populated with 12,800 silicon photomultipliers (SiPMs). In this contribution we will describe the design of the RICH and discuss progress towards the fabrication and characterization of the focal plane components.