Not a bad idea really. FB is pretty universal among the 30 and under crowd. Not everyone who uses it is crazy about it, but it's a good system for keeping in touch with people. I am not real clear on the setup for business but there are plenty out there that use it instead of or in addition to a mailing list.
I hadn't thought of it, but I'll definitely be making use of it once I'm ready to start selling my work. I'll also be setting up a web site which I'm already constructing so it's ready. I think knife making is a craft that is very well suited to the online world. There are a relatively small number of people doing it, even if you include pure hobbyists. The potential market is huge, but for any particular knife it might be fairly small. This makes it tougher to get your work in front of the right person. Online search allows someone to search for what they want and if you do your part right your work is presented to them. It probably won't replace face to face sales, but even there it makes local customers more likely to find you and make contact. Facebook makes it easy to keep in touch with customers with minimal hassle, and makes word of mouth much more effective for people who uses facebook.
I use it for a number of firearm related companies I buy from. They post updates about sales, special buys, upcoming events, new products and general company PR. It is a lot more cost effective for them than a mass mailing through the postal service and lets them put out more timely updates.