Capo for Radius Fretboard?
Instruments- discuss specific features, luthiers, instrument problems & questions
Dana, I was just going to respond to your personal message, but I saw this forum, so I'll respond here instead.
More and more luthiers (including Folkcraft as an option) are making radiused fretboards, but the truth is that unless you barre with a single finger like Aaron O'Rourke or Stephen Seifert, it doesn't really offer an advantage. Then again, if more of us had radiused fretboards, perhaps more of us would barre with a single finger!
I bought a dulcimer from Terry McCafferty, but it was before he started offering the radiused fretboard as an option.
If the Ewing capo works, then you have your solution. The Spider Capo should work once you get the hang of it. Ideally you would want a capo with the exact same radius as the fretboard.
David Beede provides a radiused capo with his models that have radiused fretboards, so you might contact him and find out if he can sell one separately, but unless the radius is exactly the same as the Bella, I am not sure it would work. According to the website, Bella dulcimers have a 12" fretboard radius. Terry McCafferty used to sell capos that matched his dulcimers in design, but I don't know if he's started making radius capos. You might send an email to both of those luthiers and see if they can help you.
This is all pretty new. If more luthiers begin making radiused fretboards and that exact radius becomes standardized, then I'm sure someone will start making radiused capos to match.

Working on the railroad, dollar and a dime a day/Give my woman the dollar, and throw the dime away