Pair of black horn button templates/moulds.
This type of template was used to make 18th century style wrapped buttons.
https://trc-images.nl/collection_images/hires/2018/2018.3376a-b.JPG#\\TRC-SERVER\TRCSharedWork\TRC Database\collection%20photographs\2018.3300\2018.3376a-b.JPG#