From my personal stash, an unused vintage Brass Nut Blank, ready for your own tooling, with curved bottom for easy application

Perfect for that new neck to add the nut to, or you just to replace a worn bone or plastic type for some better quality in your older neck. A brass guitar nut will greatly improve sustain, clarity, tone, brightness and tune-ability. 

Perfect for several brands of electric guitar. 

Dimensions are approximately: Thickness (3.50mm), Height (5mm), Length (43mm) 

and the bottom is curved