I’m not quite clear if my response will be helpful, but here goes:
We have a very nice page on our wiki about the Sherline Mill, which includes specifications, fixtures/supporting tooling, etc.
https://dallasmakerspace.org/wiki/Sherline_mill
so if you’re wanting to know about stock sizes, etc. I think that referring to that page is going to be helpful.
If you’re asking about what “milling is”, I’ll refer to Wikipedia:
Milling is the process of machining using rotary cutters to remove material[1] by advancing a cutter into a workpiece. This may be done varying direction[2] on one or several axes, cutter head speed, and pressure.[3] Milling covers a wide variety of different operations and machines, on scales from small individual parts to large, heavy-duty gang milling operations. It is one of the most commonly used processes for machining custom parts to precise tolerances.
So the Sherline can do “milling operations” (pointing spinning tools into a workpiece) on the scale for which it is sized (physically able to secure/feed the stock in the orientation required for the desired outcome AND able to spin the tooling required at the required speed).
An example: Chris Marlow mentions having used a (her own, but it’s the same as DMS’) Sherline Mill to create the fixtures for her tiny chairs here
This brings up a good point…
I wonder how hard it would be to gather some “I made this on {toolx}” pics or the like into a {wiki, or other web page} collection, and/or get some prints and post them nearby their respective tools…