T-nuts for 5mm (and 6mm) 2020 Extrusion Slots

I have a Taz 4/5 and a Taz 6. I made a top mounted spool holded for my Taz 6 and found the the slots in the 2020 extrusions were 5mm instead of the 6mm wide on the older model.
I have metal T-nuts I bought on Amazon, but they are 6mm wide. I tried grinding them down.
Did not work too well. So I designed some 5 mm wide t-nuts for M3 screws which worked OK.
I made some out of PLA, PETg, and ABS. I used an M3 tap on most but you can get away with just using a screw to cut the threads. I hav