Cob Oven: Using a form for the sand dome

Using a cardboard form for the sand dome makes a usually challenging aspect of an oven build super easy.

Using a pencil or chalk, draw out the circumference of the dome on the firebricks (28” diameter circle). Cut a piece of cardboard 7” high and 90” long (Circumference = Pi x Diameter and add a couple inches to overlap). Set this on top of the chalk circle and tape it together. Now you have a form for the bottom of your dome.

Fill it with sand and make sure the form stays over the chalk circle. After the bottom is full you can start to form the dome all the way to the 18” top. Easy peasy!