This may sound like a lil‘ bit crazy. We have an experiment and we can‘t find clay! So, I couldn‘t think of an alternative for ceramic clay I thought of mud :(
Home Depot sell several different lengths, so you should be able to get something at least close to the 1 foot you need. They will also cut it down to 1 foot for you for free.
try a scrap yard -- one of those places that buy metal
Check with a machine shop / welding shop. that makes things from Copper tubing. or Maybe a Plumber.can guide you to something that might work.
Mud is not necessarily clay. Individual clay particles are very small. Mud can also include sand and silt, neither which behave like clay does. Soil scientists determine the amount of clay in a sample by feeling it, and forming a ribbon of the material between the thumb and forefinger. If you can form a ribbon an inch long before it breaks off, it's about 20% clay. 2 inches mean about 40% clay. Any more than that means you've got something that you can use instead of clay, provided it's the right kind of clay. Many clay minerals are not suitable for use as ceramic clay, because they shrink when they dry, cracking the dish, pot, cup or whatever you made. Kaolinite is the best clay mineral for pottery and ceramics. If you live in the southeastern US, kaolin is the dominant clay mineral in the soils. If you live elsewhere, you may have a lot of other clays in there, too. If the subsoils in your area have a lot of clay (the subsoil should typically be 10 to 24 inches below the surface, but this can vary) experiment with it. Work it in your hands and roll out a flat piece to dry. If it cracks, you won't be able to use it as an alternative. If it doesn't crack, it might have possibilities.
Ceramic clay IS mud You need to clean out the roots and stones though. There are a couple ways to do it. What do you plan to do? There are some things to consider if you will be firing the piece. You may also find that your local mud doesn't have good handling properties. Depending on how you plan to form the piece, you may need to take that into consideration as well. But I will say this - Native people all over the world have found ways to use whatever mud they find around them and create functional and even beautiful pieces from it.
