How to Build a Full Size Coal Forge by Don Meador: from Commonly Available Metal
This design uses commonly available angle iron, sheet metal, nuts, and bolts. The project requires simple hand tools with the exception of something to cut the angle iron...All the pieces are assembled with nuts and bolts. Since welding is not required, the coal forge is a good project for either seasoned or beginning blacksmith.
Even though the book is mostly on how to construct the forge shown, details of how the dimensions were determined are discussed so that the plans can be modified for anyone's particular needs.
Decent plans at a reasonable price. Get a copy. Good plans. 8 1/2 x 11 booklet 36 pages illustrated.