You could always cut the cable in half, preferably near the console/port, then splice it together again. Then you only need the 1/4" or however large a cable is.
Sorry I probably didn't fully explain what I was doing, I had limited time (
which became redundant, not only to not finding out the wii plug size before the sun went down, but standing on my jigsaw and breaking the power plug... so by the time I can get the chance to go back to bunnings, my wii controllers will have arrived... anyhoo...)
What I'm putting together is a stand to hold console controllers, using "laboratory 424 wall clips" which are made to hold controllers. There will be 40 wall clips as well as another 4-12 slots for the square-ish controllers that don't need clips, like NES, SMS etc. Although it will be on wheels it is not meant for portability, just as a storage rack for the controller.
The cords will just drop directly down, and then go through the holes I've jigsawed/routed out in the vague shape of the console/company logo, to dangle straight down the back of the unit out of sight. Just for cosmetic purposes. They can still dangle down the front and since I'm lazy will probably end up like that. But the idea is no winding / rolling / binding / tying / kinking up of cords. No need for cutting or splicing any.
So, in the meantime I am actually still after the size of the wii classic controller plug.
edit: got one in the mail today, so all good. On track to finish this weekend hopefullly.