When we were in Nijmegen at the end of August, I bought five little boxwood thread reels from Bikkel & Been. Monica, who made them, told me they were based on a London find, that was originally in bone. They are perfect for fine embroidery silks, because boxwood has a very smooth surface, that won't damage your silk.
Have a look at Monica's website, they make lovely things. For now they only have a Dutch site, but when I last spoke to her she told me they are in the process of building a new site that will also have English pages.
1 day ago