Alternatives for for bottom blast forges are legion. Truck bell-housings
(the cast iron bowl between the gearbox and the engine) works very well.
Plough shares with a steel rim welded on also works.
You can even use a wooden box if you use a sufficient thickness of fire
clay to line it.
If you can't find fire clay, you can substitute it with still wet unbaked
clay bricks. Most brickyards will let you have as much as you need for a
nominal fee. The wet bricks can be cut with a sturdy blade or with a
hacksaw. Make some clay slip (a runny clay paste made by mixing some of the
clay with water) and use this to cement the bricks together. Let the bricks
dry out for a few days, then make a large wood fire over the whole clay
surface. DON'T use any air blast for this first firing. Clean the forge
after it has cooled off, fix any cracks that might have formed with some
clay slip. Then you can go ahead and light your first coal fire with air
blast.
Clean a clay forge out every 5 days of use, inspect for cracks, fill
these up with fire clay, refractory cement or even potters clay after
wetting the crack with some water.
Blowers:
Any high volume low pressure fan or blower will work. The best are
"squirrel cage" blowers. (Ryobi makes a portable one that can be used as
dust extractor or shop vac with a suitable flexi pipe connected to the
inlet. To use it as a forge blower, connect the forge to the blower's
outlet.
You might find old hand-crank forge blowers at second-hand dealers or
even at junk yards. A day spend disassembling, cleaning and oiling the
moving parts will be well spend if you do find one of these. You might have
to replace the sealing gaskets as well.
