Crap, I thought thos was going to be for tobacco stems. I have a whole grocery bag full of them from shredding last year’s crop.
There are lost of people who have stems, but the you’ll have to do some measuring, and even then you’ll most likely have to cut the stem down to fit, especially if this is to replace a broken stem on a briar. Your best bet, if you are not proficient at carving, is to find an expert to do it for you.