Some of you, like ChuckC, like to serve your strings by hand, and others, like me, prefer a serving tool. So, for the gadget minded, here's how to make a serving tool. You don't need professional metalworking skills for this or expensive machinery. A power drill is helpful, but not necessary. A hand drill will get the job done. A vise is also not required. 2 blocks of wood or pieces of metal will do.
Materials: a steel, brass or aluminum strap 6" long by 1/2" wide and about .020" thick. Can be a bit thicker. This appears to be very thin, but once it's bent and the spool of thread is in place it will be stiff enough. The store bought one uses 9/16", but i couldn't find the width. A 3" long ¼" hex headed bolt, fine or coarse thread. The commercially made one I have uses fine threads and my homemade ones use coarse. I can't say there's a difference as far as adjustability between the two. 2 flat washers, a rubber washer, wing nut and masking tape. Also, a 5/64" and ¼" drill bit.
The photo shows 2 rubber washers. I found out later that one works fine.

Hmmmm. A challenge....
You now have committed yourself to building the ultimate string server in front of the entire forum.
We're waiting...
I am actually looking ar robotics and AI to serve strings for me. Might have to do a build along.
I have one similar to it.
Good job ! I like it.
Pretty neat "gadget" Ira.
Have fun with this and use hardware with different finishes. I used stainless, brass and black.
Assemble as follows; flat washer against bolt head, insert into server and spool and out the other end of the server, rubber washer, flat washer, lock washer and wing nut.
You now have a string serving tool.
Final bends 1 7/8" from the ends. This can be 1½" or 2". You can fiddle around with that measurement. As you can see, I didn't follow the original measurements exactly.
2 more bends 5/16" from the center.
First bend in the middle.
Holes drilled and ready for bending.
Here's a steel strap cut to 6½" with masking tape applied and center line marked. One hole will be dead center and one hole on each end is 5/16" from the end.
I suppose I should show you what we're making. The fancy one on the left and mine on the right.