Why not go the shrine room route ca. 450 BCE? That means you either meditate, or are practicing mindfulness, or are trying to keep the precepts, and so forth. This "embodied shrine" can be very efficacious, and also quite subtle, in cases of familial roommate static.
Otherwise, in lieu of memorization, Dhamma books on a small bookshelf can also serve as a shrine and offered respect the way they likely treat their Bibles. Handmade or purchased bookcovers can be used if the cover imagery is problematic.
Multivalent symbolism is your friend here, e.g. a Jesus Necklace of some kind (not a rosary, sounds like you've got some Protestants afoot), though instead of a cross you can obtain a symbol for water (rivers, stream-winners, but also baptism) or fire (passions to put to rest, also the holy spirit) or the international peace symbol, for example.
Drape that necklace on a statue of a seated Jesus figure in meditation, and due to the long hair it can stand for an early bhikkhu on a long retreat.
And so on.
"And how is it, bhikkhus, that by protecting oneself one protects others? By the pursuit, development, and cultivation of the four establishments of mindfulness. It is in such a way that by protecting oneself one protects others.- Sedaka Sutta [SN 47.19]
"And how is it, bhikkhus, that by protecting others one protects oneself? By patience, harmlessness, goodwill, and sympathy. It is in such a way that by protecting others one protects oneself.