I think this is fairly vanilla for a part time sub (switch), but uh, just edge me, a guy, as long as you can, without inserting me into any orifice, try to make my balls actually turn blue, without me cumming.

While I am tied up in some fashion, maybe blindfolded.

Feathers, ice cubes, light scratching / cutting, teeth, nails, reasonable use of hot wax, whatever you prefer, that isn't likely to leave a permanent mark.