I've re-created a thumb pirn in mahogany and brass. It is 1.75" D and 3.45" overall length. The spool was turned and finished with 10 applications of hand-rubbed linseed oil. The spindle & thumb ring are silver soldered from brass rod and hand filed and finished. The one deviation I made was to use a brass tube bushing in the spool. You can't see it and it significantly improves the smoothness of rotation and will reduce wear. Here is the prototype:



I am making 5 thumb pirns in total. The prototype is mine, and the others will be numbered 1 to 4 with my maker's mark. One of these is spoken for but the remaining 3 will be available to collectors, historical angling recreationists, and loyal supporters! PM or email if interested.
Cheers,
Michael