I make a lot of parts, nearly all are very simple. These won't be the most impressive parts you'll see, to say the least.
This part is intended to cover a segment of 1/2 inch all-thread that is basically supporting and spacing a shelf. This sleeve will slide over the top nut, down the thread, and cover the bottom nut and washer. A washer is then placed on top and the shelf is attached to it's mount, completely hiding the all thread, nuts, and washers.
There are also cover pieces to hide the retaining nuts/washers.
Believe it or not, this will print without support using judicious slicer settings and a very low temperature. Fortunately, it's not structural so the reduced layer adhesion of the cool extrusion isn't a problem. The interior usually has a small bird nest or two that no one will ever see.