Does anybody know what these things are called? There sort of like tiny versions of the threaded neck insert. It's like a little brass tube (1/8"? 3/16"?), threaded on the inside, and a certain size of machine screw to match. I know that there were some bass builders who were using them to attach the control compartment covers. They''re not threaded on the outside, because they're not really load-bearing. I want to make the next one with separate control and pickup compartments, to make fiddling with guts easier - no taking the strings off to change capacitors around... I just can't find the right place, or words to search with?