Through my amateur radio journey, I’ve been using chopped up plastic cutting board to make end insulators for my antennas. I figured that being a 3d printer owner, I should be using something better. I whipped up a little design for a nice looking insulator (much better than hack-saw’d cutting board) that can be printed in less than a half hour. It’s made for 12awg wire, but can be resized to accomodate other wires. I’ve uploaded the STL file here.