I have made my own mains power extension cord by buying a heavy duty (1.5mm core) 20m cable and a heavy duty male plug from Bunnings.
The guy there also gave me a leaflet on attaching the plug (I cut off the existing molded one first).
I am pretty sure that I am allowed to do this, right? It will provide an extension cable to a Dryer (which interestingly seems to have 1.0mm 3G something something written on it's own power cable that I am extending)
It says here:
http://www.energysafety.govt.nz/upload/31994/brochure.pdf
The following:
"You can fi t plugs, cord extension sockets or
appliance connectors to a fl exible cord. You can
also replace fuse wires and fuse cartridges.
However, you cannot accept payment or reward
for this work."