I would like to suggest both diamond and straight knurling be available as modelled features able to be machined or printed, as the current procedure to create a diamond knurl is very complicated and even somewhat trial and error. The advent of 3D printers has meant things like replacement (or in my case original) knobs are very fast and easy to print and can be highly effective rather than just temporary solutions. However there is presently no way to easily knurl the surface such that they replicated replacement machine knurled or moulded knobs.