Hi,
Another way to deal with the ball end vs. loop end dilemma is to buy ball ends. If you need loop ends, take a small wire cutter and carefully cut the ball away and you have a loop end ready to install.
Richard
My very favorite case is the one I got with my Blue Lion. It is difficult to find sturdy cases that will withstand baggage handlers.
Like Paul said, I have made a couple of cases using an appropriate length molded plastic rifle or shotgun case--Plano or Pelican for brand. The measurements are critical for length and height of your instrument and a bit of time may be needed to research the various measurements of the offerings available.
I removed the soft foam that came in the case. I used blue (some brands are pink) styrofoam from my local building supply store. By combining different thickness I got the depth I needed. I glued those together with special glue made for styrofoam (craft stores). Then I cut out the outer dimensions to snug fit the case. Then I cut the shape of the dulcimer inside with a little extra room at the tuner end. Following this, I covered it gluing on soft fabric--anything from felt to false suede to velvet. I typically line the top of the case with a thin later of padding and cover that with fabric as well. I had room in one to make a wooden box with a hinged lid set into the styrofoam for picks, tuner, strings, straps etc.
I suppose you could use the foam that comes in the case and cut out the shape of the dulcimer. I am personally leery of that as I had a camera in a case with similar foam and the foam disintegrated and stuck to the camera.
