Even more challenging, try and build more than one and have them come out nearly identical.

Once that's mastered then realize what's really needed is to make each one slightly better than the last, but only by such a slight degree that for everyday users they are still virtually identical.

Then what you end up with in the long run is allowed to be much different than when it started, but there are no major surprises along the way.

"Continuous improvement" is really just stepwise on a relatively different timescale.

my bottle gravel shaker didn't seem tooooooo bad

Silly observation: the garage door rolls up to reveal the Oboe maker, but the nyt subscription paywall moves up the screen faster, as though parodying itself.

Only slightly related, but skills in building instruments (or AI) are basically orthogonal to skills in playing/using instruments (or AI).

Also slightly related, the map is not the territory.