FYI for my buds here regarding the NanoVNA 3D printed case (at least the popular style).
In order to flash the firmware in .dfu mode you must short together the two pins shown in the pic until finished. If it's outside any case you can clip the pins together and all is well. But, since they do not have header pins, when it's inside the case, you cannot access the pins - they are covered by a supporting rib on the case.
I am adding header pins to the board in that location to make it easy to short out the pins either with a clip lead or a shorting block, which then means they will interfere with the case ribs. So I'm going to cut out the rib space required manually (not worth hours more printing just for this little mod). Just letting you know, if you want to add headers the case needs to be modded before printing (not hard to subtract that area in a CAD program), or you can cut it afterwards.
That is all, have a nice day.