What I have done is make a small cut in the lining under where the wrist strap will be placed and insert a small piece of sheet metal, about 22 gauge and the size of a tunie (silver dollar) the metal was pre drilled and a brass screw put through it. Then the lining is glued down. I have used a glue gun and 3M 77 Super adhesive The glue gun works best. The strap is then screwed on. I then have lined the strap with sheeps wool cut from an old coat to cover the nut

Nothing is foolproof to a sufficiently talented fool.