Simwool is a company based out of the United States that specializes in kilns and firing accessories for pottery, glass, and metal. The kilns are made by first pouring a slab mold that is formed around a steel tube. The molds are made with a plaster mixture and then are sanded to remove the excess plaster. The kilns range in size from 10-60 liters. They come in both wall and floor models. The copper tubing is inserted into the kiln and allows for natural gas or propane firing. There are two ways to control the temperature: rotation and flow of gas. The flow of gas heats up the copper tubing which heats up the clay inside of the kiln. The rotation keeps the heat inside of the clay mold which prevents it from cracking or breaking. Simwool also offers many firing accessories such as grids, casters, filters, firebricks, starters, and more