To be fair to all the many talented builders, and accomplished Luthiers, and provide a little background, I have been in this trade but two years. During that time I have the experience that comes from building 10 Dulcimers, and one Scheitholt, and the pleasure that comes from listening to my instruments being played and enjoyed by skilled musicians.
I have a lifetime of woodworking experience, and have played the guitar most of my life, so the challenge to build a stringed instrument at some point had to prevail. Like most woodworkers, I have to experiment with new techniques, materials, and tools, but my main objective is to build the best dulcimer I can, with the least investment in tools, and most emphasis on tradition. The Dulcimer is all about American Tradition.
They are various ways to prepare wood for a form, depending on the wood type, thickness, and degree of curve needed. Guitars have a distinct curve requiring a combination of bending iron, water, and/or steam, to obtain the desired shape. The shapes of most Dulcimer designs, however, can be achieved by soaking the sides in water, then fitting them into the form to dry.
The sides, top, and back were completed before starting the new dulcimer steps. I do these in my spare time and store them in a safe place. Once the head and foot are done, I match up the sides with the right back and top (sound-board) to assemble the basic form.
This is where I need to slow down, double-check the measurements, then start a new day with the assembly.
Summary: The soundboard is also a key component because of the impact it has on the sound quality and resonance. Two factors play into the determination of a top-quality soundboard; (1) wood type, and (2) composition. Wood types with dense, straight grain, such as spruce, cherry, cedar, and redwood, are most preferred. The composition relies on consistency in thickness and weight. Ideal soundboards will have long, straight grain and will be very light weight.
The photo shows examples of cedar, oak, walnut, and cherry in 4" wide strips, and joined. The technique used when joining is known as book-matched with matching grain facing in or out depending on the desired style.