A Blacksmith's anvil is by far their most useful tool, arguably even more useful than Forge itself.Unfortunately, as anyone who has done any blacksmithing work knows, good anvils are just horrendously, obscenely expensive. And so, to kick off my series of blacksmithing projects, I'm going to show you how to make an anvil that would be the envy of Thor himself.

Step 1: A Note on Concrete Filled Anvils

I have naught be the utmost respect for professional blacksmiths. That said, some of them can be real snobs when it comes to anvils, looking down on concrete filled anvils and generally anyone not willing to dole out a thousand dollars or more on a super anvil forged from the heart of a nutron star. To be fair though, they do have some valid points. Anvilfire.com has some great points on why not to use a concrete filed anvil. Concrete is the worst sort of friend, it appears strong, but as soon as it really matters, it will fail you.
The trick then, is not to rely on it too much. You want to build an anvil that would work even without the concrete. It is there mainly to add weight and solidity, and deaden noise.

Step 2: Acquiring Materials/Skills

Now for this particular anvil, the hardest part to find will be the main plate for the top. On this design I need a plate of steel that is 1 inch thick, 8 inches wide, 18" long, Along with some assorted plate and pipe. For the shell, i'm going to use about 16 ft.² of 16 gauge sheet steel. I'm going to use a whole lot of rebar to reinforce the shell. for the filler, I'm going to use about 640 pounds of concrete.

As for tools, you're going to need,
Some sort of welder,
An angle grinder,
Something to cut the sheet steel with, such as an acetylene torch, plasma cutter, tin snips(not advisable), a bandsaw, or a crap-ton of cutting weels for the angle grinder.

The main other thing that you need, is to be a competent welder. I repeat, this is no beginners welding project, you need to be able to make a weld that can be hammered on for hours without breaking.

It should be noted that I got all the steel for this thing(accepting the top plate) for free as scrap, and you could probably do the same.

Scrapyards are a great place to get the main plate. I got one that is 1 1/2" x8"x 36" for $30. The ancient, mystical redneck junkyards one sometimes finds in the woods are a great source, or ask people if they have any old doodads you can salvage steel from.

Step 3: Designing Your Anvil

The nice thing about making your own anvil, is you can make it literally however you want. It can be as whimsical or as practical as you like

I would suggest drawing out your own, but feel free to use my schematics if you like(but no plagiarism please). They're not extensive or anything, but you're a clever fellow, you can figure it out.

PS, if you ask VERY politely, I can make some better blueprints.

Step 4: Make a Cardboard Model

Whenever you're making anything out of sheet metal, it is advisable to make a cardboard model. Always remember, cardboard is much cheaper than steel, and if it won't work with cardboard, it won't work with steel.

Step 5: Cut Out the Pieces

This one's pretty self explanatory, trace your patterns on the steel, and cut em out

Step 6: Weld'n Time

Weld, Weld, And Weld Some More, And One You've Finished, Ha Ha Just Kidding, Keep On Welding.
Basically, you just slap it together the way you did with the cardboard model, but with steel.
Now for one of the most important steps, the inside supports. You want at least five really heavy duty legs on the bottom of the main plate, with a few more on the horn. Then just go crazy and weld rebar onto every available surface, there really is no such thing as going overboard on this step.

Post script: When you're doing anything with the top plate, remember to turn the power as high as it will go, and set the wire feed fairly low.

Step 7: Fill'er Up!

This step should be fairly self-explanatory, just flip it upside down and fill that thing up with concrete.

The main other thing is to make sure that you have it positioned so that once it is full you can simply roll it into place, where it will be permanently.(you can't move this thing when it's full, just don't even try)

Step 8: Make It Perty

This step is grueling, but simple. just grind until you've burned out the motors in all your angle grinders,(that's how I knew I was done) and depleted some ozone with all that spray paint.

Step 9: BEHOLD!

And lo, amid a wash of fire and smoke, where bolts of lightning flash and steel flows like water, I labored. And finally, at dusk on the fifth day, my toils were ended.
That day, Vulcan threw his hammer to the ground in dismay, for he knew he was bested. That day, the ringing hammers of the forges of heaven lay still in respect.
I heeded them not, but instead gazed in awe at what I had wrought, and saw that it was good, nay, it was friggin fabulous!