GM: "You find boots of dexterity +2, they add +2 to dex while worn & attune:yes"They both exist already. At least the +2 versions for certain stats.
Player: woah! woah woah how do I handle that?
GM: It's like an ioun stone of agility but boots
player: ok a put my new boots over my boots of elvenkind
GM: You can't wear two pairs of footwear
Player: I walk up with boots floating around my head since they are like an ioun stone.
GM: no they are boots, you need to wear them on your feet for them to work
Player: "you said they were like an ioun stone why do you make everything so complicated instead of just giving normal magic items"