My bro, Jake, wants to start a business, and I guess he wants to make knitting needles. And he wants to know what you all would like to see in a knitting needle. 
Good sharp points, but not so sharp that they hurt my finger.
Easy transition from point up to the shaft of the needle.
Whatever he uses to put on the ends must not be heavy. It will tire the hands.
Shafts must be as close as possible to standard sizes.
Quality control. Points must be centered. Must not snag fine yarn. There are sites that talk about conditioning needle shafts for a smooth finish. Google.
Attractive, but not ornate.
I wish him well.
Good points and very, very smooth. Since you knit you should be able to guide him. 
Accurate sizing.
Something that sets them apart from other needles, other than that they’re handmade (if that’s his direction). The custom-made Signature needles are a good example.
For circular needles flexible cables without a memory.
For sock knitting I would like to see shorter needles (2-3 inches) on longer cables. If I try to magic loop with long cables the needle length is longer than the 1/2 the sock circumference putting tension on the sock.
For the reason above shorter needle length on circular needles with replaceable cables.
I recently had some custom-made bamboo circs made in tiny sizes so I can do socks on one tiny circ instead of DPNs, magic loop, or 2 circs. So I would love to see more options for custom circs. They’re just made out of bamboo with plastic tubing in between. Unfortunately, these ones aren’t as smooth as I’d like and the joins aren’t that great. I have another full set of 16" bamboo circs and the plastic tubing joins are perfect and smooth, but the custom ones stink.
How about needles that you can identify, like two different colors so you know which row you are on kinda thing.
The size on the needle somewhere so I don’t have to worry about loosing my needle gauge.
Thanks everyone!!!
Since you knit you should be able to guide him.
Wanna bet??? :roflhard: 
I too would say the pointy ends - & smoothness! I hate when the yarn tugs on the needles. Some people like that so they dont feel like they’ll loose their yarn. I like the slippery!
A nice smooth cable is nice too for circular - & no cornered edges on circulars where they meet the cable.
I also like the needle size visible on the needles as well…
What sort of material is he thinking of using - wood? metal? How cool a thing for him to start thinking of making! You can always test drive all his samples!
He’s using wood at the moment Becjo!
Thanks everyone!! I’ll keep passing the suggestions on.
I keep telling him the tapering of the point is very important, but he seems to think as his sister, my job is to hinder him in any way possible. LOL But he keeps asking my oppinion, so I guess that’s a start. LOL
Ask him if he will need testers for his needles. I will be glad to be the first! Any one else?? Rubie
Does he knit?
If he’s going to be making needles, it would be good for him to experience what knitters feel when they manipulate yarn with needles. Learning to knit would give him plenty of feedback in terms of needle weight, smoothness, point sharpness, balance, etc.
no he doesn’t… I’m trying to get him to. But that may be a struggle. lol