Creating a triangular mountain dulcimer -seeking help

G'Day all. In a posting on Pinterest  “Lumberjocks” briefly illustrates a simple triangular mountain dulcimer he made for his wife, based upon  2 or 3 pages titled  “Crafting a Mountain Dulcimer” found in a  Readers Digest publication “ Back to Basics”.  I do not have access to that publication - but I am thinking of building a Tennessee Music Box using zither style tuning pins  (triangular would be different). I favor a rectangular shape keeping it small. Overall length determined by 23-25 inch vsl.  I guess the style and construction would beafter the style of the very intriguing entry level cardboard dulcimers made by David Cross at Backyard Music Instruments. I would love to try one of those but exchange rates plus international shipping costs to Australia takes it out of  my"bucket". Given the wide range of interests of FOTMD I would welcome any information, with grateful thanks from "down under in Oz". My sincere best wishes to all, in this most troubled world. Stay well.