The first thing that i did, was to get my blanks. I only had some rough blanks, so i had to plane them down to the right thickness first. In my project, they are 5mm thick, so the assembled locket will be 20mm in total. The edges are not so important, as they will be worked over later. Make sure you have enough of your blanks to fit at least 8 (it's nice to have a little extra, if somethings goes haywire) slides on to them.