Actually, I have to admit, that headline is borrowed from Don Bies, droid wrangler at Lucasfilm during the filming of Episodes I – III. The same line was used for his preparations for the prequels.
However, on a much more hobbyist scale, it also applies to any R2 Builder in the world.
Building an astromech is not a quick job, as there’s no “complete kit” available, and it can take years to get to a point where you can say your droid is finished. And once there you soon discover glitches. Things break, the middle foot rattles, the dome turns too slow, etc.