Step 1: Make it !
0 = collect
If you live in a popular area in a city, you are probably passing everyday by a lot of garbage, pay attention. I was lucky enough to collect wood (brown), stupid posters (green), industrial plastic coated felt (grey), dead bike tyre (black), yellow foam bed (yellow).
What you need to buy, or you have might have them before hand is 2 metal plates to make a lock support, construction thread and a big leather needle.
1 = wood work, the bones
Assemble the wood boards in 2 main parts, a little differently profiled so once they fit, they won't move too much, but for now they must move independently. Nail strongly the boards and be generous on the glue.
1b = coating, the skin
I glued the poster I found in the streets to coat my case. If you want it more water proof and stabilised you can varnish it. I want it too look garbage and look worst as time is passing, so it has to be structurally strong, but the skin must be fragile.
2 = the lock
Screw the 2 metal plates so the wooden box gets tightly closed if you forget it in the street. Make sure the screws are not accessible from the outside of the case. The lock shouldn't be too big not to attract too much attention by it's size or the sound it makes.
3 = Binding the case, articulation
Prepare the holes in the bottom of the case. The holes must be big enough to allow you pass a big needle and many thick threads many times. Cut the dead tyre, adjust it to the case, leave a little more length to it, you'll cut it after sewing with construction thread from the inside. Do the same with another piece of tyre, from the outside. Cut the extra length of tyre. Your case in binded.
4 = the elastic straps
Sew 2 rubber straps to close the case. I like it tight because i hate the idea to see my laptop getting out and crashing on the floor. Sew them unlocked (easier without tension).
5 = the outer bag, the protective clothes
Cut a large piece of felt, sew it with construction thread by the same previous holes. It can be too hard where there is too many layers of rubber (where the straps are passing in particular), try harder but don't damage the straps, they are fragile (narrow) and under continuous tension. I also found a bet with which i made the handle of the bag.
6 = the foam bed, the flesh
Make sure the first you piece of foam that is placed is the one at the bottom of the bag : when in use this part will be the more solicited. Adjust it to the case, adjust the foam to the computer size. Leave always slightly "not enough space" for the computer for it to be under pressure. I recommend to put a thin layer of foam between the computer screen and the keyboard, in case of major shock.
I have been using this case for 3 years now, i had some bike accidents, fell on it cycling, fight in the street with it a few times, many rainy days ... and the computer is the one I'm using right now to write this instructable, covered with crappy stickers but it works marvellously, my beloved Swiss knife. cesar