You may purchase a homyo-jiku at any shop of articles for Buddhist altars, or request the chief priest of your o-tetsugi-dera temple (an ancestral temple of the Jodo Shinshu school, equivalent to a bodai-ji temple of other schools) to prepare it.
仏具店などで法名軸を購入して用意するか、手次寺（他宗でいう菩提寺）の住職に用意してもらう。