Drilling the end pin hole before closing the box avoids some time consuming cleanup of wood chips later. When drying varnish outside it’s nice to be able to hang your cello upside down as well as right side up but fitting a trustworthy hook into that large hole is a bit of a problem, wooden bungs tend to shrink in the heat and drop out. I made this expanding bung out of parts from the hardware store and it has proved quite reliable.
It’s a threaded rod with a rubber bung squeezed between two washers. Drill the hole in the bung and adjust the taper with a rasp while rotating the bung on your drill press. The spacer keeps the threads from getting varnished and it keeps the wing nut out of the way of your varnish brush. Wrap the bung in teflon tape to prevent varnish gluing the bung into the endpin hole. (click on picture to expand)