bullet connector(s)
thingiverse
Depending on the accuracy of your 3D printer, you can select bullet connectors with varying degrees of width disparity.
Download Model from thingiverse
With this file you will be able to print bullet connector(s) with your 3D printer. Click on the button and save the file on your computer to work, edit or customize your design. You can also find more 3D designs for printers on bullet connector(s).