Ink-saving pattern for background

Hi everyone!

I am an Industrial designer, so not so much experience with printing, but I could not find any information searching the web about this topic:

Short: Is there some pattern, that would be recommended for background to make white objects visible when printed but would save more ink that using solid colour?

Long: For our customers I prepeare print files for product graphics, most of it is white. Till now our company used dark grey for background (70% black). The customer often prints this document on A3 to write into it some comments/changes. I can imagine the ink usage is huge. We cannot create always some additional file which would be only for this printing. My first step would be to try lighter grey (one which would save more ink but the white object would still be visible). But I've also read once that there are special ink-saving fonts, with dots inside, so I am looking if there is maybe also some pattern that works similar way?

Thanks