Givi AF266 screen- help with mounting hardware

I bought a second hand Givi AF266 screen that’s missing a couple of bits and bobs: the M5 bolts, washers and spacers.
I’m guessing the M5 bolts and washers will be easy enough to find, but do the spacers need to be a particular size? Can I just replicate them with a stack of washers? If so, how deep should they be? 5mm? 10mm? Nylon or stainless? Thanks!