I have a fetish for bruises. I love seeing beautiful blue marks over my lovers body, of which I'm am responsible. Here's the question:

Which sex toys make the best bruises for the least amount of pain inflicted? My goal is to bruise as much as possible while not oversteping my subs limits. Or maybe it's not just the amount of pain that's the factor, more like the kind of pain? Not being a spankee I'm really not in a position to know.

I've got a wide variety of toys and I'm damned if I can see any obvious system here. Is the thickness of skin a factor in which impliment to chose? or does thick skin only mean I've got to hit it harder?

Any advice would be apreciated.
thanks