At first I only printed one of the lower corner sets to see how it would fit together. The latest GitHub master had fixed alignment problems and everything fit well together.
My main tools for assembly were a 2.5mm ball end driver and some spring loaded tweezers. Forceps would work as well.
Here Re some instructions that go with included pictures. I am writing this with my phone and will have to make them inline later.
Populate these four hole locations of each frame_motor piece with 3 x 8 mm screws and jam nuts.
Attach each corner with two and M3 x 20 screws. All screws should be loose at this point.
Load the other two corners with screws and nuts.Work these in to the extrusions at the same time with the screws loose.
Slide in vertical extrusions.
Once together go around and firm up the screws.
You can test mount the motors with M3x8 screws. Using tweezers can really help with this step.