[malloyd]

There is no obvious reason for the form to vary. Maybe even the opposite - Shinto shrines for example have elements they are all supposed to have regardless of which kami is enshrined there.

In most religions minimal home shrines and the like seem to consist of an image of the god or saint (or equivalently a holy book or symbol) with something to elevate it (a shelf or platform or hook on the wall), a lower platform for offerings with a suitable container (a cup or bowl for water, wine or rice, or a candle or incense holder), maybe a curtain or cabinet around them to close the shrine off from view of the unworthy, and enough space for a worshipper to kneel, sit or prostrate himself in front of it. Certainly anything fancier is unnecessary - a successful religion can't really require a lot from a personal shrine, because it isn't going to stay successful if the masses can't afford to practice the faith.