I jury-rigged my own years ago. Found a piece of plastic (actually it was a bank cheque folder) that was narrow enough to fit in a breast pocket, long enough that it reached the bottom of the pocket and stiff enough that it didn't bend. I pinned my medals bar to the top (if the material is more puncture resistant, pre-form the holes with an awl). The pocket piece isn't seen above the medals, completely fills the pocket so they don't move and the medals are easily unpinned if needed to be worn with a uniform. It ain't rocket surgery.