Didn’t realise that. Just measured the hole sizes in Nettfab. So the hole diameter is 3.6mm and the slot for the nut is around 8mm wide.
That doesn’t match up with anything that I have here anyway. My M4 nuts take are 7mm between flats. M3.5 are 6mm between flats.
edit: Just measured the imperial MPCNC nut trap in Nettfab. The hole and nut sizes are exactly the same as the IE version. Maybe the wrong file is uploaded to thingiverse?