Wago Back to Back 221-412x2 + 221-413x1 Clip

Use m3 screws mount up enough Wagos to bring single phase mains power into a project box. The three way connector covers connecting the chassis to ground. The mount holes are 27.5mm apart (compatible with the V connector mount holes)

Print with the common edge down, 0.3mm layers, no supports.

If using this with high voltages or current, you should probably print it in something like https://www.prusa3d.com/product/prusament-petg-v0-natural-1kg/ (Bump the size a few percent if you do, that stuff shrinks.)

Though it's pictured with ferrules in use, I can't recommend them, the holder introduces a tiny lip and the ferrule boot/strain relief catches on it. Perhaps a bare ferrule could work if you wanted.