To re-create Zundapp special tools 2500 k 5 -2 and 2500 k 6 – 2 which together get adjust the steering column locking nuts with everything but the handlebars in place, I started by taking measurements of the locking nuts:

To create the socket wrenches we need two tubes of steel, ideally hardened.

The first tube will move the small top ring and needs to be slightly larger than 38mm diamter and not larger than 44mm diameter. Once ordered 4 ‘teeth’ can be cut out of the pipe. This will then fit the nut from above:

I ordered stainless steel pipe from e-bay used for handrails. Outer diameter 42.4mm and 2 mm thick making an inner diameter of 38.4mm which should just fit the small nut.

The second pipe needs to be slightly larger than 45mm and not bigger than 49mm diameter. I ordered pipe of 48.3mm outer diamter and 2 mm thickness, so 44.3 mm inner diameter. Mostly this is either handrail pipe or exhaust repair pipe.

This, with 4 teeth, will fit over the smaller pipe and move the bigger nut: