Step 1: The Design

Dimensions:

800mm height
300mm width
1200mm length
340mm between the shelves

I used L-shape metal bar, the dimensions are:

3mm thickness
20mm length

Then, I placed the MDF planks on the racks

Step 2: Materials and Tools

Materials:

MDF wood
L-shape metal bar

Tools:

Arc welder
Clamps
Metal Cuting Wheel

Step 3: Frame Cut

I went to the local hardware store to buy and cut the following L-shaped bars:

4 pieces 80cm long (for the legs)
6 pieces 120cm long (shelf frame)
4 pieces 30cm long (shelf frame)

I did not made a frame for the middle shelf.

You can adjust the dimensions according to your needs.

Step 4: Shelf Frame Assemply

Before the assemply of the shelves, take each one of the 4 small pieces and make a cut on both ends, so that it can 'hug' the long pieces (see pictures).

Weld just a bit on the outside surface, so that it can be a nice rectangle frame.

As it is welded a bit to keep its shape, turn it over carefully and then weld it properly underneath.

Make 2 of those frames (for the upper and lower shelf of the library).

Step 5: Bookshelf Assemply

When the shelf frames are done, just weld the legs on the outside of the frames (as in the first picture).

The top shelf goes all the way to the top of the legs.

The bottom shelf is about 6cm from the lower end of the legs.

Now the library should be like a big iron framed box.

The middle shelf is nothing more than the 2 remaining 120cm long bars, welded between the two shelves.

To prevent the books from falling, add a 3x20mm straight bar on each side, that connects the top and the bottom shelf.

Step 6: Wooden Shelves

I used 3 MDF planks (29x120)cm and 19mm thick.

Because of the thickness, the wood is about 2mm above the frame (you could use 17mm thick mdf, if you want the frame and the wood to be at the same height).

Step 7: The End

And... the bookshelf is ready!‼

The universal law of horizontal surfaces dictates that once they exist, they are occupied. Τhe bookshelf isn't the exeption, so after some time it's hard to find an empty space and mess is inevitable !! :P