A small (feed-forward) DM in the lab is fantastic for saving on cost, but can be a little awkward to fit in. The documents below show one way to fit a DM with a 2mm pupil in to the CHARA lab, replacing the BRT secondary with a BK7 lens, a flat, the DM and a new paraboloid. The original intention was two curved mirrors and a DM. From MJI's email of 5 Feb 2012: “ I'm thinking that if a 3 reflection option doesn't work, possibly an option with two achromats may work, especially if we can ignore lambda < 550nm.”
The DM mount size has halved since this original work. MJI has checked the effect of this, and the second paraboloid can be made a little less off axis, but there isn't otherwise much change to this setup. The xlsx file should probably be ignored but is a good starting point, and the ZMX file only has a 1mm pupil on the DM, when it can be 2mm.