A variety of supplies are used in pen making. Generally, "supplies" are consumables, that is they are used up over time in the process of making pens.
Although some tools get "used up" in that their edges dull or they require periodic replacement for some reason, those fall into the category of Equipment. Likewise, items which become significant parts of the finished product, such as Pen Blanks, fall under the category of Raw Materials. When a supply item is generally used only with a particular tool, such as the compounds used with buffing wheels, you'll find those discussed with the related tool.
There are often several options for various supplies. For instance, there are many types of Sandpaper, several choices in Glue, and a wide array of products for Finishing. The following are supplies typically used in pen making.