This is by far the most time consuming part of the build. Here are some advice:

Places to visit:

1) Vehicle recycling yard

Here we are looking for only one item: a large drum brake. The one I got came from a Van, any vehicle this big or bigger can have a large enough drum brake. Don't even look at car ones because they are way too small for our application!

2) Metal scrapyard

Bring a good pair of gloves and dig into the pile! You'll need many stuff here :)

How to approach:

The key to stay on the cheap side is to pick up what they have and especially those pieces that don't have much intrinsic value like rusty mild steel.

Find a spot where you are not into the way of none and make it your own product design spot.

Improvise with what you find: this forge can be done in hundred of different ways just walk around look for sturdy mild steel pieces then when you find something suitable lay it on your spot.

Take your time!

What to take home:

Thick base plate

Legs: three or four (three way leg is easier to level)

Thin top plate

Square tubing to build edges to contain the coal

A tubing of some sort from where air will be blown inside the fire. A "T" joint is prefered

I won't give you any measurements so that you won't look after some precise pieces, again, the key is to get what you find! :)