Model originally uploaded to Thingiverse at https://www.thingiverse.com/thing:2002327.

Simple bracket for mounting a 240W Power Supply (12V 20A 240W model S-250-12 Eccanixity purchased from Sourcingmap on Amazon UK). The power supply has four M3 threaded holes spaced at about 84mm x 126mm. The bracket is secured to the 20x20 extrusions on the printer with an M4 screw and nut, and the power supply attaches with M3x6mm screws (one at the top should suffice - the lower hole may be hard to access from inside the printer).

These brackets leave 5mm clearance between the PSU and the printer, which is enough to clear a 220mm heated bed, and also provides some space to fit a cover over the mains voltage connections.