Here is my alternative for bobbins on a budget. Golf Tees in hard wood 4” long. I alter the tips. I sand them so they are more tapered and not so blunt. A light sanding also on any rough areas but to my surprise they are pretty smooth already. I only use these with my small looms. My Mirrix 16” aka Big Sister and frames I’ve built. The tapered tops built into the Tees works great and the yarn stays put. You could add dowel toppers to them for added length. These are the longest I’ve found. Golf Galaxy 4” Tees in natural hard wood 75 count in a bag for $4.97 . Oh and if I remember they are made from birch wood.
Here is a pic showing the tips as they come and then after I sand them to be more tapered.
So if your just gettting started with tapestry weaving and your not sure if it's for you or not this is a great way to get some bobbins going without the expense. Now with that said, nothing compares to a lovely handturned brass tipped bobbin which I adore but these can get you started while you start to collect those beautiful brass babies. John Moss makes wonderful brass tipped bobbins and so does Ian at IST Crafts.