You need a bookshelf with mixed wood and harmonic light design?
This bookshelf has no visible screws and you can staple or organize books as you like, because of different shelves. It is light and beautiful. The hard part is the construction afterwards you will need one day work. This bookshelf can be plugged together and just needs to be mounted on the wall.

why not:

mixed wood --> warm and light structure
close-to-wall-construction --> maximum used space
fibonacci/golden cut --> harmonic
curves --> get closer to the wall for small books, and get the wide in the middle for A4-script

we need:

4 planks
5 shelfes/boards
4 iron angels and 4 screws for wall and 4 small for wood

Step 1: Construction - Use Fibonacci

strong wood

Thinking about the construction you have to be careful to let enough wood left for the weight it will have to carry. I heard people say that the bookshelf will be too weak and instable. In my case I had 56*17 mm^2 area for each of 20 joints. The last 4 joints have the maximum load to lead from the board to the plank. But as it is not perfect let´s say that just the half of it will really carry.

With :

loadstress*safety-factor <= comprehessive strength

and in the simple case of uniaxial compression:

loadstress = weight*9.81 / supporting area

((4*57*17)/2)*(comprehessive strength) / 9.81 = maximum weight.

Even if you have a safety-factor of 5 and a strength of 40N/mm^2 you will get 1,5 tons. But as it is just an approximation, reality can do things else. A sharp edge could case a crack and also moisture is a weakening factor for wood.

what is beautifull?

You need some regularity in your construction. Use same lengths if possible and try to follow the rules of the golden cut. But don't stick on it too hard. In some cases there is a new length you cannot use anywhere else and it won't matter. There are also some factors like perspective and so on. So it will not be usefull to use fibonacci or the golden cut strictly in the shelf-depth.

The most important thing is the regularity and the direct partition!

Fibonacci and the Golden ratio

Maybe everyone heard about some rules that make things look well-ordered and somehow beautiful. This rule is known as the golden ratio. The Fibonacci sequence mathematics are interconnected with the golden ratio.

Fibonacci sequence: 1,1,2,3,5,8,13,21,34

golden ratio: phi = 1.618033...

The golden rule is (in our case) telling us something about the position of an seperator between two areas. So area1 and area2. With the golden ratio you can make the bigger area1 phi times bigger than area2. (area1=phi*area2) The areas together are (1+phi)*area2. So you get two measurements out of one given.

For example you need space for books (height=20cm) you can go into the fibonacci sequence and use 32.360cm or 30 cm for the second seperation. Now you would have about 50cm. Now you may recognize the fibonacci sequence 2,3,5.

I used the 2m planks, the first shelf starts at 70 cm. So we have 1,3 m with books. This factors I can just use once. And I used 50 and 30, 15 and 25 cm on every part.

curves

When drawing the curve: Don't forget that the wood-pieces are used for the whole length. The curve needs two ends that are parallel to the wall to get a smooth wave.

Trick: if you have a long metal ruler you can hold it parallel on both ends and the right shape will show up.

Step 2: Sawing

Now you need some practice in woodworking or passion to make nice connection parts. The holes for the wood need to be 1mm bigger than the thickness of the wood to get easily (!) together. If your wood is on room-conditions you can try with less. But you shuld saw less and work the last mm with sandpaper. This way you will have a nice tight and strong connection.

Get your boards together and check the holes. It is very important that the holes are perfectly at the same point. Otherwise the wood needs to bend to get in and gets stress. You will have to bring power into the system to get the bookshelf together. Making a 'bad' hole bigger and add some mini-wedges afterwards is solving the problem.

First saw what is possible with your tools and than use a chisel (as you probably know from woodworking joints).

Note:In my case I needed a lot of testing and sanding to get a good connection. The reason was that my wood was not even and somehow warped. In your case it should be a fast work.

Now sand and oil your wood.

Step 3: Gettogether

A thing you can do now, is to cut out ledges so that there is no distance between the wall and your bookshelf.
get the plank to the wall --> it should be parallel and as close as possible to the wall!

This part shoul be fast done. Get the shelves together and lean it on the wall. Check the connections. You may need some mini-wedges for loose connections.

Make some different wedges.

But don't worry too much, the weight of the books will hold the shelves in possition. ;)

Step 4: Fix It on the Wall

My construction is stable itself but on the wall it would tumble. Our bookshelf does need some little support to just stay on the wall, because the main emphasis is not in the angle of your planks. Get a friend to help you at this point.

Ask your friend to hold the bookshelf in position
get a leather and mark the top of the plank
hold the angle behind the plank,
1. remove the plank and
2. mark the point for the screws on the wall
screw the angle into the wall- but use just one screw
do this again for the 4 planks
screw the angle from the wall into your wood and voila - you are ready

In my case there was a pipe behind three of my planks. So I fixed this bookshelf-half under the bottom of the last shelf on the wall. The second fix was between the bookshelfhalfs.