When I go to play my hammered dulcimer and don't know what I want to play, sometimes I just start playing notes pretty randomly in the following patterns, and it sounds amazingly good even if I'm not thinking about it at all! You ought to try it too....
The "marked courses" on my model of dulcimer (Dusty Strings D600) are white, as they seem to be on most brands these days. When you play them in a rectangle you get the first, fourth, fifth, and eighth (octave) scale steps of one key. Try it! It sounds intriguingly hollow and rustically sophisticated.
Now, what if you go from key to key doing the same thing? the same sound goes shifting into different frequencies like a well-constructed composition that has "minimalistic" limitations --- and you don't even need to understand anything about this to make it sound that way! So experiment with playing any and all marked courses on your instrument (without playing any unmarked --- black --- courses at all), and listen for the remarkable effect it brings! Play slowly, play quickly, move up and down in steady patterns, jump to opposite ends of the dulcimer's range, and listen for what you get.
And what about the "unmarked" black courses? You can do the same thing with them! Limit yourself to just the four black ones in the rectangle of a single key. These are the second, third, sixth, and seventh scale steps, and they form a more clustered, impressionistic effect when you play only them. Try the same approach of roaming around the dulcimer with these as you did with the whites, and listen for this unique sound!
Now --- what I tend to do with these is to explore all whites for a while, then shift to all blacks for a while, then back again, and it is very quickly a stunningly polished and interesting musical effect.
When I play background music at an event and am coming to the end of one piece and don't know for sure what I ought to play next but don't want the sound to stop, I may launch into these patterns briefly while I ponder the next tune choice, and it creates an amazing artistic mood with no effort! Numerous times people have come up and asked me what composition I was playing at that point! (Hmmm... What should my answer portray?)
Please, oh please, try this absurdly simple technique! It's really worth it!