I made 3 furnaces from bricks using different configurations to test their effectiveness. The benefit of using bricks to make a furnace is that it's quicker, easier, re-useable and portable relative to a furnace constructed in-situ from clay. This is because the old furnaces crack and need repairs where as the brick ones can be assembled and re-assembled with any broken bricks being swapped out as necessary. Also, the shape and height of the furnace is easily changed by adding/subtracting or re-arranging bricks. The first furnace used a square plan with the bricks laid on their sides with a inner cross section of 18 cm square. A 2.5 cm diameter tuyere was used and about 15 g of iron was made. The second furnace was the same but used a 5 cm diameter tuyere. It made about the same amount of iron. The 3rd furnace was a haexagonal plan furnace with a diameter of about 22 cm. The smelt yielded the same as the square ones for the same input of ore, charcoal and effort.