Sorry coming late to the dance. I've just finished making two turnscrews for one of my rifles. I found the metal part of the demo absolutely magic, I actually got them to work. I don't have the woodworking tools or skills to make the handles but on ETSY I found some very nice handles made in Sheffield that worked out very nicely. Here is the first website:

For George Barnsley https://www.etsy.com/listing/1717565135/mini-rosewood-gents-wooden-handle-turned?ref=user_profile

for his sister company Woodware Repetitions in Sheffield, England https://www.woodwarerepetitions.co.uk/handles
I found they gave fast service at reasonable prices.
I hope this is of use.