Some years back Folk-Legacy released an LP "The Hammered Dulcimer and How To Make It And Play It" by Howard W Mitchell Folk-Legacy FS-43,which may be of interest. This album came with a totaly absorbing illustrated book of instructions which recounted Howard W Mitchell's attempts at building a hammered dulcimer and included much information on stringing and tuneing and explaining why the lower notes should be thicker strings and the higher notes should be thiner strings. The note a string will be tuned to will depend on the length, diameter and tension. Have you plans to "invent" some form of automatic constant string tension device ? Then you realy could say "...it was in tune when I bought it".