Select an area well away from any source of combustible materials. If you are building a fire pit in a park or other public space, be sure to check with the park officials before you begin. Many parks have strict regulations about the size of the fire pit you can construct, and where that fire pit can be located. Since you are building a temporary fire pit, you need to be able to return the area to its former condition as easily as possible. That means you may want to make the fire pit smaller than you would if you were building one for permanent use.
Lay out the dimensions of your fire pit. Place a stake in the ground at each corner of the pit and wrap those stakes with twine to create a square area. Make your fire pit as large as you need it to be, but keep in mind that the larger you make it, the harder it will be to take down and haul away.
Dig down approximately 12 inches inside the perimeter of your fire pit. Keep the ground as level as possible while you work. Try not to disturb the surrounding grass and sod too much, since you will need to fill the dirt back in and smooth it down when you are done.
Lay down several inches of paver base on the floor of the fire pit after you have dug it out. Paver base is available at many hardware stores and home improvement centers. Make sure the paver base is flat as you lay it down. You can remove that paver base and haul it away after the temporary fire pit has served its purpose.
Use pavers to create a perimeter around the fire pit. Lay the pavers next to one another until you have the entire perimeter covered, then stack more pavers on top until the perimeter is the height you want.
Place fire-rated bricks along the interior walls of your fire pit. The smooth side of the brick should face toward you. Stack the bricks tightly so that there are no holes or gaps between them. You want the surface to be as stable and uniform as possible.
Wait for the fire pit to cool down completely before you begin to disassemble it. Even after the pit has cooled, it is a good idea to wear a pair of heavy gloves, just in case some of the bricks and paving stones are still hot. Deconstruct the fire pit by piling the paving stones and bricks in a wheelbarrow and hauling them away. Chip up the paver base and discard it, then fill the hole you made back up with the dirt pile you created when you dug it.