Tack Welds

The filter ring fit over the spherical trim ring around the lens, and so was somewhat self aligning although it did want to slide a bit. Lacking any solid reference features, I aligned it parallel to the face of the lens as best I could by eyeball, then applied a few drops of cyanoacrilite glue to lock it into place for the epoxy.

And yes, the rig is mounted to the front of my microwave.

View the resulting timelapses here.