A fire pit cover will help protect the unit against fading and rusting, among other common effects of exposure to the elements. If your fire pit did not come with its own cover, you have several choices for making a cover of your own, from simple cloth to a hard wooden case.
Simple Cloth Fire Pit Covers
The easiest type of fire pit cover is made from ordinary cotton or wool fabric. It can be constructed by sewing a circular top panel onto a single side panel that wraps around the fire pit, or by sewing a square top onto four side panels, which are then joined at the corners. With moderate sewing skills, this type of cover can be created quickly, especially if you have a sewing machine available to speed the sewing of seams.
Inexpensive Vinyl Covers
If your fire pit will always be exposed to the elements, you may want to go with something a little more weatherproof. By using a vinyl shower curtain, you can make a fire pit cover as described above, with the added bonus of being resistant to rain and snow. The main problem with a vinyl cover is that it is vulnerable to ultraviolet rays from the sun, and will deteriorate if left in direct sunlight for long periods of time.
Durable Canvas Covers
For the same protection as vinyl and a lot more durability, consider purchasing a section of canvas and cutting your fire pit cover pattern out of that. Use the same guidelines as above, with a single top panel and one or more side panels, and stitch the seams with a heavy thread. A canvas cover will probably be the longest lasting soft cover you can make, and is very likely to outlast the fire pit itself.
Hemming a Sewn Fire Pit Cover
For a better seal, you can easily add a stretchable lower hem that hugs the base of the fire pit but can be easily pulled off. To do this, allow 1 ½ inches of extra length when cutting the side panels. Fold that extra length over and sew it in place to form a simple hem around the lower edge. Insert a section of elastic hem, and sew the end seams together to anchor the elastic in place. Alternatively, you could substitute a piece of flexible cord through the hem opening, which can be pulled tight and tied securely.
Thinking Inside the Box
Another idea is to build a case the fire pit could be stored in when not in use. One suggestion is to convert a sink cabinet so the fire pit can simply be slid inside the open front. This has the added benefit of doubling as a useful counter top even when the fire pit is being used, which makes it the most useful type of cover, as well as being the most expensive. A box cover is probably not well suited for large fire pits, and will not work well at all for in-ground pits, or large combination fire pits and grilling stations.