I designed a thread stand to be used with thread cones and cross-wound thread spools (for sewing machines that don’t have horizontal spool pins). To make the stand a bit more substantial, the base can be filled with something heavy, like sand, lead shot, or bearing balls. The conical spool cap has two diameters: wider for bigger spools, and narrower for smaller ones. To make it you need a 3D printer, some glue, and 12-gauge steel wire for the center pin and the arm.
The new-to-me Singer 411G came with spool pins in a horrible state. One was broken, the other one was sitting askew. A quick web search reveals that each pin consists of four parts – the actual pin, a rubber spacer, a plastic washer, and a spring nut. Replacing it requires removing the plate with the information on decorative stitches. The best description of the process and a list of alternative solutions can be found on this page. If you want to keep your machine close to original condition, then you can stop reading my article right now, and head over to the above link. I dislike the idea of replacing the bad design with the same bad design; I wanted steel spool pins.