I have built a frame for a jabod. Its about 2 ft by 2ft square. 6" deep. 3/4" tuyere 2" above bottom board. My question is about the fire pot. I have no clay around. I was considering filling it with sand and forming a fire pot from plaster of Paris and sand. My previous set up was just play sand and the fire pot would collapse in too often. Sometimes while forging. Any suggestions for material? I have a budget of about 20-30 bucks right now. Thank you and I will post a pic tomorrow.  I also wonder if 6" is deep enough. I may add 2" . 

Cheap kitty litter is regular old clay and is cheaper then plaster of Paris. 

I thought about that. I could probably fill the whole jabod with it too. Do you think I would need to grind it fine first? I worked with it once and ground it in a coffee grinder but not on this kind of scale. Perhaps a blender from a thrift store. 

Just make sure you get the clay based litter.

it's clay, just wet it and let it soak, once it starts to get mushy, you'll want to work it and you also want to mix some sand into it You could mix the sand dry before wetting the clay if you wish)......best way to do it is put it all in your box put your wellington boots on and stamp about in it. Once it's all mixed, shape it.

As regards the deeper fire, use any clay mix you don't need to make some bricks ( cardbord boxes for molds) these can be positioned around your fire to regulate the size as needed.

I have heard it works better ground or smashed up. If you look on the jabod threads I believe they mention the ratio of clay to sand. ( it's escaping my mind atm) 

You’re going to want a layer of adobe at least 2 inches thick covering the entire firebowl and the top surface of the forge. The rest of the space can be filled with sand, clay, or just basic dirt.

The adobe should have a sand:clay ratio of somewhere between 2:1 and 3:1. Mix up your dry ingredients, and stir in enough water to moisten the entire batch. Let it sit for a while to give the clay time to absorb the moisture, and then mix it again. Pack it into your JABOD and let dry.

Cat litter doesn’t need any extra grinding, if you give it enough water and time to hydrate properly. 

Do not try to save money here. Always use NEW kitty litter.  And please, don't ask why. (grin)

A 5 gallon bucket or a plastic tote with a lid works well, your going to case the clay by setting it and letting the water be scorned by capillary action. By letting it sit a day with the lid on it equalizes. Buy leaving the lid off it will dry out some, place Th lid back on and the crust will get wet again. You need mud pie consistency to mix the clay and sand well, and yes stomping is most effective, but hands work, it can be dumped out in an old plastic tarp and kneaded as well, stiffer is better as it dries faster, adobe bricks are easy if you want to go that rought. A 2x4 frame mold and remove the frame move on to the next, but hand forming is fine

with the there so low you would be good for depth with charcoal   

Thanks for all the information. I will be working on it on my next day off.