The MX3 beamline will extend the capabilities of the existing suite of MX beamlines at the Australian Synchrotron. It will allow collection on crystals that are too small or weakly diffracting for the current beamlines. A high level of automation will transform membrane protein micro crystal collection and high throughput projects such as drug and fragment screening. The optical design of MX3 is in progress and a preliminary design has been produced. The proposed beamline would produce a full beam at sample of 8x2 µm (HxV, full-width half max [FWHM]) at a flux of 6e13 ph/s at 13 keV and as small as 2x2 µm beam at 1.8e13 ph/s. Simulated data show crystals with maximum unit cell lengths up to 400 Å can be measured using an 16M hybrid photon counting detector. Sample positioning will be provided via a goniometer and robot combination what will allow 6 second sample exchange. Serial crystallography capability will be provided using in-tray screening and collection and fixed-target silicon chip scanning stages. A dedicated cluster will provide real-time data processing and automated data collection will be standard. This will include automated location of crystals from a rastered volume with subsequent data collection on each crystal with resulting automated data merging from multiple crystals. The high degree of automation, including unattended data collection will allow very high throughput of crystals. The high performance and automation of this beamline will allow drug/fragment screening approaches to be applied to systems that were previously not viable due to small or weakly diffracting crystals. The MX3 beamline will allow our users to solve the structures of increasingly difficult membrane proteins and large macromolecular complexes.