For this simple forge you will need several usual items:
A hair dryer (In the final version I used 2000W hair dryer FS-09 with the cold air switch)
An iron pipe (non galvanized) I used about 1 m long and about 1.5 cm wide pipe
A piece of hose (wide enough to fit the pipe, at least approximately) I used about a 50 cm long hose. It helps you -manipulate the forge because it is flexible, but probably you could connect the hairdryer directly to the pipe.
A duck tape (Optional)
A plastic bottle (I used 0.5 and 1.5 plastic bottles)
Step 1: Cutting the pipe
Cut the pipe as on the photos.It would probably be easier with the proper tool.
Step 2: Putting everything together
Cut the bottle near the top, and drill a hole in the cover so the hose can come through. Leave a little bit of the bottle so it can cover the opening of the hair dryer. Connect the hose, pipe and the hair dryer and wrap the connections with the duck tape.
Step 3: Placing the forge
Dig a channel in the ground the same length as the pipe, and place the pipe as on the photos (point the opening up). Cover it with stones or bricks to stabilize it and surround the place where the fire will be with the same material.
Step 4: The problem
The hairdryer on the photos is the cheapest hair dryer from the Chinese store (about $2), and the problem is overheating so it melts the hose, the duck tape and even itself. I ordered online a new hairdryer ($20) that can blow air without heating and I will add more photos and a video tomorrow when it arrives. That is actually the only cost of this forge. I would just like to publish this instructable before the great outdoor contest finishes (tonight) and I will finish it tomorrow with the new hairdryer.