Bone lace bobbins come in many styles and sizes.
Standard Midlands styles average 4 1/8 inches in length and 1/4 inch diameter or thicker. These bobbins are made of commercially sterilized cow bone and take much longer to turn, due to the hardness of bone and the curvature of the blanks. The difficulty of finding good bone may also produce a slightly shorter bobbin. Once they are turned, they are sterilized again, which also whitens them a bit.
Twists must be a little thicker than your average bobbin. Creating a full twist literally removes about a third of the material, so there must be enough to keep the bobbin strong.
Wires are inlaid into the bobbin, not laid on the surface. The same goes for size 15 seed beads, which require a much deeper channel.
Many of these styles are available in Bucks, or travel sized bobbins, though the design may have to be simplified a little to fit.
And yes, they are drilled for a spangling wire. The drill hole is not large enough to hide the knot; I do not encourage putting the knot in the bobbin because that will wear the bone as the spangle swings, and can cause the tail to break.
