Dont know about any free forges, but they can be fabricated for around $100--depending on what materials you can scrounge and what you have to buy--you need a 85 cu ft/min blower and some short pieces of 2' pipe ---a metal box----some refractory material [rigid or soft] and some elbo grease ,-or you can stack one up out of refractory bricks---You need to make a good one if you are going to weld in it.-If you are not going to weld you can rig almost anything to heat steel to do general forging.