Make a basic blacksmith forge by connecting a blower to a fire pot with a pipe. Also create a hinged trap below the fire pot to remove ashes left over after burning. Use charcoal as fuel for an authentic forge.
Make a simple fire pot by repurposing metal objects that can handle heat, such as a metal fire pit or a drum brake, or use heat-proof bricks to build a fire pot. Build some kind of lip around the fire pot so the heating metal balances and does not fall out of the pot.
Attach a pipe to the bottom of the fire pot, aiming straight down. Put the hinged trap at the bottom of this pipe. Attach the blower pipe to the middle of the hinged trap pipe at a perpendicular angle. The air blower keeps the coals in the fire pot burning very hot. Use a hairdryer for the blower, but make sure the pipe is long enough that heat from the fire does not melt or damage the hairdryer.
To work the heated metal, you need an anvil and a hammer that can withstand the high temperatures. You also need a bucket of water to cool the metal down.