Buying off the shelf is not practical, gears have an odd bore and some of them odd tooth number.

Thanks for the suggestion johngoodrich, I will put up a RFQ. I found 1.5mm long neck bits for £15 at shop-apt.co.uk, but only 1.2mm flute length. That is 9 passes for 10mm stock, I can see why a shop couldn't be bothered at that. But I'm sure I can find better.