Here is the pattern for the faux leather rucksack I made. (add a waist belt?) You can see the scale at the bottom right. If you make sure the red line is 10 cm when you print out the pattern, all the pieces will be th.
This free backpack pattern features zipper and a fold over design; the top folds down into a stylish and practical backpack with an unusual design. I found this tutorial in the Russian page otkroysunduk.