We've recently been re-evaluating the utility of mounting FED externally to a cage or behavioral chamber, rather than placing FED3 in the cage itself. To faciliate this, we modified the front plate to include 4 magnet holes/mounts, and created a drill guide pattern for modifying the wall of a chamber to mount FED3 to it. We also used the "mini-hopper", which is available in the files area.
For mounting on a chamber or cage, it only requires drilling four 5/16" holes (for magnets) and two 2" holes (with a hole-saw) for the pokes and feeder. I was able to drill these and insert magnets in about 10 minutes. Video below, please contact me for modified FED3 front plate design and drill guide.