Question on how to make a part - ( very small splines )

[rgray]

Another source that you may look at is Stock Drive Components. (I think that is the name of the outfit.)

http://www.sdp-si.com/
Lots of good stuff from them.

 

[4GSR]

Here's some spline shafts and hubs sold by SDP. They are in the diameter range but not fine enough to match that in your picture.

https://shop.sdp-si.com/catalog/?brand=sdp&cid=p206

Thanks Russ for the link.