He started Saturday morning at around 10:30 with a trip to the lumber yard (the colored plastic had been acquired earlier in the week), and worked until sundown.
Our kids (and one or two others) lent him a hand.
He screwed the roof on around 8 p.m. and called it a night.
Sunday afternoon was spent installing the front door, a drop-down table and some shelving in the corner.
As of Sunday evening at 6 p.m. the house was fully functional. Future plans include some sanding and painting, a door latch and perhaps a plywood floor. I guess that subscription to Family Handyman came in handy (ha ha) after all!