I know what you mean Im wearing a padlock as we speak how do you put up with it digging into your legs?
easy, just use a small enough one, like for luggage.
this prevents intercourse AND
and if you want to use one for chastity from masturbation, you only need have a piercing or two (course you can't have comb or key) and attached a kali (tube with inward facing stubs which do not need be sharp) tube with it.
it is fairly comfortable when flacid, yet horribly horriby painful when if fully errect, just uncomfortable when half erect (of course it's hard to cum that way), and if you get the diameter right, it's not too horribly painful erect but enough to make cumming near impossible