I'd love to have a digital scale that will beep as the weight rises closer to a pre-set value.

Seems like acaia is in the best position to do this, but I don't think it has a buzzer built-in. Maybe the app can do that.

Scenario is:

I pre-set my target brew ratio, say 1:2.
I weigh empty portafilter, it's auto-tared.
I grind, and weigh portaftiler with coffee, it's recorded, say 18g.
I lock in portafilter, put scale on drip tray, add cup (and auto-tared).
Now start brewing, I will then steam milk, or do whatever.
As the weight gets closer to 36g, say starting from 30g. The scale start to beep, like a boom, more rapidly as it gets closer.
I then know when to stop the brewing, even if I'm still focusing on streaming the milk and not looking at the reading on the scale.

Cool idea. I think it might be really hard to implement. Stopping a shot right on target takes some anticipation since it happens closely. Unless the shot pulls quite slowly, I'd guess we'd just have a quiet scale and then full missile lock beeping suddenly. But of course someone should be able to figure this out. Like a PID that just loops back to a speaker instead of a device to control.