I am building a set of wheels and they require double square nipples becuase I must hold the spoke very close to the thread to stop the spoke turning, and so double square nipples come with a square on the inner side..(rim) and therefore it makes sense to use a nipple driver..as you can't get a conventional spoke tool on the open side of the rim, as it's too close to the spoke and the tool I am usiing to stop the thread turning.

Here is my problem..the nipples are 3.5mm square, not the 3.2mm that i have a driver for and shops are trying to sell me a driver for, becuase obviously they do not fit...I have tried to find an appropriate driver and emailed Sapim..still waiting for a response..I should be able to get one of Aliexpress, but the donkey delivery will take about a month to get here.
So far 5 bike shops have been unable to help me..is there any one out there who knows what tool I need? brand, and where I can get one?

Get some DT double squares or squarx

are these ones you suggest 3.2mm then?

yarp