When Lutestring and I went to see the Crowley exhibition in Sydney, the Altar was both more elaborate and more chaotic than that.
Me, I tend to sprout little Altars or shrines everywhere. I have three or four detectable ones in the living-room, two in my bedroom, two in the front room, one on the front doorstep, one on the garden table, and an attempt at one in the back yard. You could even mount a reasonable argument for the theory that the top of the hot water service in the bathroom also constitutes an Altar of sorts.
This seems to be the minimum I can get away with, as I live alone. Remind me to take pics when I get home.