Let's start with main equipments.
2) Lots of thick nail like these ones
4) Ruler or Meter
5) Pallets (35 unit) in the dimensions of 260cm x 15cm (You can change it according to your need)
Step 1: Preparing Sides
Bring 4 of the 2.60 long pallet parts together and attach them into each other by using horizontal small pallet parts in the dimensions of 60cm x 15cm (Cut them from other longer pieces). Use 3 of these horizontal parts for preparing one side.
See the picture. Attachment places of the horizontal small pallet parts are marked with red rectangles.
You should prepare 5 sides like this in the length of 2.60 m and 2 sides like this in the length of 2.10 m.
For the 5 longer sides don't attach horizontal small pallet parts at the very edges. But for the 2 sides that are in the length of 2.10m, attach only the 1 of the 3 horizontal small pallet parts at the very edge.
Step 2: Attaching and Arranging Shelf Carrier Parts.
For the shelf carrier part you should cut 6 more pieces of small horizontal pallet parts in the dimension of 60cm x 15cm
Before giving the U shape that you see in the picture, we should attach these shelf carrier parts into the 2.10m long sides. Attachment distance between 3 of the small horizontal pallet parts on one side must be identical at the other side.Otherwise your shelves will look inclined.
In the picture you can see the red markings which are our old horizontal pallet parts. And you will see green markings which are our shelf carrier parts.
Step 3: Giving U Shape
It is time to give U shape.
Put one of the 2.60m sides at the bottom. Then put one of the 2.10m long side vertically attach them into each other by adding 50cm long small pallet parts which are marked in red color at the picture.
Edges of these small parts are cut with the angle of 45 degrees.
Nail all the parts. You can nail as much as you want. But don't use more than necessary.
Step 4: Attach Shelves
It is time to attach shelves. Attach remaining four 2.60m long sides as shelves. One of them will be the top side.
Don't forget to nail them to 'shelf carrier parts' from above. Also nail them from the outer side of 2.10m long vertical sides.
Step 5: Canceling the Moment
It is time to get rid of from swinging. Attach 4 more 50cm long small parts into top part of the our wooden shelves. As we did in the step 3 'Giving U Shape'.
As a final touch. Add one long pallet from left upper corner to right lower corner. It must in touch with our 50cm long small parts. See the red arrows in the pictures.
To be safe with our heavy shelves we need to add pillars in the middle of our shelves. See the green arrows. Height of these pillars depends on your desired distance between each shelves.
Step 6: Here Is Your Huge Shelves
Have fun ! You paint it into any color that you wish :D