I know ED received two red styli. As I told him in my communications, they are his free and clear with no obligation to use them or comment on them. His comments would be welcome if he chooses to comment on it.
The 'best' example I created was actually using the tungsten dart barrels, though those were actually a bit too heavy - and too rough as the texture tears up my fingers over extended use.
I suspect that the, 'ideal' version of these is going to be a <5mm diameter dart tip on a solid stainless steel stand off with male threads on one end, female threads on the other with a flat top screw as an end stopper/catch. The stainless steel stand offs would likely need to be manufactured to length, and with the needs to tap or thread both ends, it could wind up being difficult to do that at a reasonable cost.
But, with the materials I have from the last round of experiments, I should be able to come up with the proper specification for it. I would also like to add some texture to the standoff/barrel. Ideally it would have the end stopper/head 'built in', but that would require starting with 7mm dia stock and turning it down to 5mm for 98% of the length. Sticking with the flat screw into the end might be more cost efficient as it would decrease those turning costs. Then it would just be a matter of finding a machine shop that wants to crank them out in batches of 50-100 or so.
A larger catch might be that I'm not interested in starting a stylus business. So far I've done the research on an intellectual lark.
So - if someone has a machine shop connection and wants to take over the idea, I will gladly give them my input to make their product the best it can be.