Would it not be more economic just to buy a stick of brass bar of the correct diameter and make the nuts from that? It is a lot easier to hold a nut that is still attached to the end of its parent bar (for thread tapping or slot cutting) than it is an individual item.
Yes, good point. I really do not know if simply buying a brass rod is more
economical(?).
I have a fair amount of it on hand, that I purchased at auctions, yard sales (
tag sales on you side of the pond?), and the like.
I will do that if it is required for a proper fit, but I find turning small brass threads vexing at times. On the other hand, tapping brass is simple. What I can say is that it is a lot more work!
The small carriage bolts are good "as is" from the factory for one half of the project. No fuss.
You then only have to fabricate the other half (the slotted nuts).
Brass
nuts are ubiquitous and inexpensive compared to brass carriage
bolts, which are decidedly difficult to source (in that smaller size) and expensive. Purchased nuts are (of course) already tapped, relieving you of the need to tap a lot of small items.
Turning the nuts is, by comparison, easy. You can simply mount them on bolts of the proper size (with the head cut off), secured in a chuck or collet. I "gang" turn them, multiples at a time. In that manner, they lock themselves in place. The slot is easily cut with a thinner hacksaw blade or a screw-slot file if you do not have a mill.