[MadMax]

the cost of the screw isn't much of an issue, but it does mean an extra machine operation after the bottle fitting is turned on the lathe. One of the biggest factors determining the cost of a part is number of setups. If a CNC machine can crank something out in one setup it means that there is less operator time. For a part like the bottle fitting, setup time is significant compared to the time that the machine is actually spinning.

The probe requires two setups. One side is machined from long barstock and they're popped out automatically. There isn't much operator involvement as the first operation can progress fully automatically. To machine the mag probe end, an operator takes each part blank machined from long barstock and puts it in a lathe chuck once more to turn down the other end and drill the other half of the centrebore. Because of the second operation, the probe costs more than double the cost of the bottle fitting although the bottle fitting requires more material removal.

Consumer products are a PITA to design. you have to develop something that works well with little training. Error tolerant and failsafe. Durable and cheap. There's an adage I like:

You can have it good, cheap, or quick. Pick two.

Consumer products have to be good and cheap so I blow my brains out spending a lot of time in product iterations. V4 is actually V14 in my book. The worst part is that most of the ideas that didn't make it look quite plausible in thought. Once a proof of concept was hashed out reality bites and an unobvious problem kills it. The end result is the distillation of a few good ideas pulled out of a bucket of plausible but ultimately wrong bad ideas. The end result works for obvious reasons so it looks like a highschooler could design it. A lot of product design is acquiring a lot of "know how not". It's definitely exhausting.