Footage (or half metre) markings on wire, so you can easily calculate how much wire was used on a job. That or an on-site off the roll wire printer which can be programmed for that, and wire numbering as well.
Switches, especially 3-way, in the form of:
https://www.electrical-contractor.net/ubb/Forum1/HTML/006219.html Not for the benefit of rough/finish electritians, but for the home owner, so they can replace the switch without ruining connections.
4 wire cable, and 2 and 3 wire made for switch loops (with blue in addition to, or instead of white).
Plug in ceiling/wall light fixture fitting, for the same reason of the plug-tail recepticle/switch.
NEMA 3A dimmable incandescent lighting recepticle configuration.
