(Pictured above: What appears to be an innocent little fan was a menace to be reckoned with! Really, though, I’ll admit to having a bit of fun figuring it out.)
5/4/19
Building Summary: Today I wired in, connected the ductwork to, and seated the bathroom exhaust fan.
Commentary: Compared to recent building summaries, this entry’s may appear lacking, but in this ensuing commentary I shall describe why it was not a mundane feat. First of all, the fan’s wiring box was tinier than anything I had ever wired before – about 2 inches deep, 2 wide, and 2 ½” long. Into that orifice, I had to fit the two included 14-gauge wires, the three incoming 12-gauge wires (that run to the on/off switch), 2 tan wire nuts, plenty of electrical tape, and the backside of the receptacle into which the exhaust fan connects. It was not an easy task for an amateur at electrical work, but with a substantial bit of time, effort, and learning I was able to fit it all in with adequate neatness.
A neatly connected ground wire. 
A packed electrical box ready for covering. 
Exhaust fan set into wall (much to my relief). 
Exhaust fan with cover placed for added satisfaction.
This was followed by my attaching the 6″-to-4″ duct converter via bolts and tape and then by my discovering I could not fit the fuselage in unless both the fan and electrical box were respectively removed and unseated. Fortunately, those two tasks were not near so difficult as making the discovery itself. The unit commenced to fit into the wall very snugly (almost too much so for comfort, but it worked nonetheless). After the fuselage was in place, I fastened it in with 1-5/8” self-tapping screws, reseated the electrical box, and then shifted in the detached fan. For additional satisfaction, I twisted on the covering even though I knew I would need to remove it whenever I finish the wall.
The difference in taste (between mutton and beef) was novel. It was an enjoyable lunch.
Final Note: Tomorrow I plan on neatening up Jacobhouse, building the kitchen sink’s base cupboard, and then if there is still time, I will begin installing the doors / shelves in all the cabinets I have already built. This will clear up space in the bathroom (my next work-target).