just get some more tattoos all down the arm. take your time.
i think people are so fixated on having the "sleeve" look ... if you want a sleeve, you get er all designed and done at once (multiple sittings). otherwise just load that god damn arm up with a variety tattoos. whatever makes you happy and inspired and feel confident. it doesn't have to match. puzzle piece em. tile em. layer em. just get the tattoos 🙂