I’ve printed a few knobs for sticks, mostly out of photopolymers when I was working in that field, wish I’d printed a few in powderbed.
im assuming you’d be looking to get a filament machine, and depending on how capable it is, I think you’d have better results for the knobs with something like PETG or ABS over PLA, as it would be more durable for the application. Another thing I would be concerned with when it comes to PLA is weak layer to layer adhesion, especially with what I am assuming your design would look like with several unsupported layers in overhang.