nut5 use flat M5 nuts with this in 5mm 20x20 extrusions T-Slots

As the original nuts where to expensive, I use this to hold regular flat M5 nuts in place. They are ment to be "tight", so you might have to play around with the size from 98%-102%.. Just push in the nut with something round of its size,. If the part breaks, it is to tight, if the nut just slides in, it is to wide.

I used DIN 439 M5 flat nuts 2.7 x 8mm