Mine are all wound, for a nice full bell-like tone, and I believe mandolin strings were used. I had our best local repair guru do them and he chose beautifully. I believe he got two strings out of each mandolin string. The hard part is the gauge for the lowest strings-- they get real mushy and dull sounding with the wrong ones. If you like, ask Barry Finn to take it to a good repair person and apply calipers to see what the gauges were-- he still has my good one.
Let's discuss movable do. Instead of the card under the strings, I use a narrow strip of paper wound all the way around the thing, with letter names marked (no accidentals), and they slide to make the lowest string (and scale from there) read as any note name I want it to read.... this means that I can read any diatonioc music in its range and instantly transpose.... the paper thinks I am in the key the piece is written in, and my eye thinks so too, but the psaltery knows perfectly well it's in D all the time.
I use D so I can play most of the Carolan literature, altho it's as low as this seems to be able to go, without mushing out on the low end. The key of A is too high for the tone.... F & G also work well but if your strings can work for D, you will be able to play with lots of folks, as you know, for fiddle music.
I'm also learning to pluck two-string chordal accompaniment for someone playing melody...
You will have SO MUCH fun with this-- and be aware of its deep healing properties as well.
The other one also is all wound, and the gauges are all nuts-- it does not sound nearly as nice.