house altars ive found, can be used for small blots and food offerings, have sections added for specific patron deities, and can work as a small faith/protection source for the household its located in (especially if the entrances are ringed in with protective runes).
usual components are:
-oriented north somehow as best as can be managed in the furniture layout
-ritual knife (doesn't have to be sharp by default unless you're using blood. otherwise its just a pointer tool)
-bowls/cups/both of these items, for food offerings
-appropriate decorative items like planters, plants, display stage boxes or colored cloth
usual uses are:
-offerings (hot food and drink are easy to access and give. feed it like any household member)
-protection of the household and its members
-recharging of energy for magic and wyrd
-the gods talk back and listen during a blot
-show up disheveled and dirty, get disheveled and dirty treatment from the gods. show up clean and respectable, get clean and respectable treatment from them instead
-food offering quality. the fresher, tastier and more homemade it is, the more it is generally acceptable
-shrine enclosure/placement. a shrine must often be tucked away or hidden for when guests come, since paganism is hard to generally explain, and not everyone must get shown everything. at the same time, it has to be public, pretty and open in the house because it is, after all something to fawn over and attend to. i have mine out in the open in a photogenic birds cage, but ive seen others have shrines hidden in closets or in side rooms on small tables
-materials: precious metal and crystals are the most ideal. non-precious metal (although gold paint is your friend here), glass and wood under that. plastics, rubber, artificial materials lastly under that.