Hello Anders,
This is typical lamellar armor. I did domething very similar on my Attila the Hun figure for Poste Militaire many years ago.
The way I did it was to create a sort of "stamping" tool. This was made from a few pieces of evergreen strip plastic glued together in an overlapping manner just as the scales appear in your illustration. The little bits of lacing were represented by carving small holes into the individual scales. The tool works best if it only represents two or three scales at the most.
The individual rows of lamellae must be done one row at a time, starting at the top since each succeeding row overlaps the bottom of the row above. You simply start from one end, carefully pushing the tool into the soft putty. The previously impressed "scales" are used as the 'index' for lining up the next ones in line.
Once you have impressed a complete row of scales, the tops of them are carefully shaped with the knife and toothpicks. Final sharpening up of the upper edges should be done with a sharp knife after the putty has hardened. You must let each individual row harden before doing the next to avoid smooshing the detail of the previous row.
Yeah, i know, this takes forever to do! But it was the best solution I came up with at the time. Take a look at the Poste Militaire figure of Attila to see how the effect looks in the end.
Good luck............ and much patience dude!
Mike