Before you get started, I suggest that you might want to take a couple things into consideration.
How much space do you have?
Will your altar be permanent or temporary?
How much stuff do you plan to put on your altar?
If you want something big, you've got to keep in mind how much space you have to not only place the altar, but to have ample space to move around it if you wish, or to move it elsewhere if need be.
If you can leave your altar up all the time without fear of guests coming over and getting upset at the site of an altar, or if you don't have to worry about pets or kids disturbing things on it, then you have a bit more freedom in choosing whether you want an altar that will remain stationary versus something that's easily portable.
If you do choose to go the portable route, wheels and handles are great additions to your altar.
If you plan for your altar to hold every conceivable tool, make sure that what you choose is suitably sturdy. An empty cardboard box can make a nice portable altar in a pinch, but it might collapse under the weight of a half dozen tools and 20 candles in glass jars.
An altar is the work surface that you deem sacred for your purposes. Cleanse it, empower it, and away you go.
