Hi NightCabbage,

I took the liberty of poking around a bit with your file and within a few minutes I was able to get a chamfer (I went with .25 units). I rebuilt several of the surfaces. I split the offending surface block in half, rebuilt the top and side and closed the bottom (probably not necessary but I wanted it to be a solid when I finished). After a little clean-up, the edge in question chamfered nicely. I'll attach my attempt. Is this going to be a space ship?