Vintage dulcimer information sought
Instruments- discuss specific features, luthiers, instrument problems & questions
That is a really nice looking dulcimer Art.
I believe the little feet on the sides of the bridge are to brace it to keep it from slipping to either side from uneven tension of the strings. This feature is useful for dulcimers that can switch between 4 string equidistant and 3 course with paired melody strings. The four string anchors in the tailpiece of the instrument are equidistant.
If you wanted paired melody strings, because the string anchors are set up for 4 string equidistant, the inner melody string would want to pull the entire bridge sideways, and the little legs on the sides of the bridge would brace it to prevent this.
The only issue is you would need pretty deep slots so make sure the strings cant pop out of them.
The benefit of a spacer is that it has very deep slots so that the strings put tension on the sides of the slots and are already the correct distance apart before coming in contact with the bridge.
It might be worth considering to make a nicer looking, more precise spacer rather than not have one, if you are planning to play with a doubled melody string, and not 4 string equidistant. An advantage of having a spacer (and corresponding slots in the nut) is that you can switch between 4 string equidistant and paired melody strings more conveniently.
Also, as Ken suggested, you should check that the action height and bridge placement are correct, especially before reducing the height of your bridge by making slots.
Good luck!
Nate

Cross harp, what a concept! To play straight on the harmonica, your tonic is the 4th hole, but to get those blue notes, your tonic is the 3 hole. I still can't play like Sonny Terry, but I can manage some amateur blues and have fun.