[Finster]

Hard to say what size the cylinders to use because it all depends on what machine you are starting with (and how big it is). I'd go to the various manufacturers websites, look around, see what sort of information is available to download and then pick a model. Then it might be listed what the full size machine uses like (bore, stroke, rod dia) if not and there is a diagram/illustration scale it up to the size you want to make and go from there. Another option is to use a diecast static model to measure and scale but that can introduce errors sometimes and with much smaller scales sometimes the details are missing. Hope this helps...