An LLC does several things. First, if you are scrupulous about your personal and company funds, it protects the personal assets of the members of the corporation (LLCs have members, not owners) in case of litigation. Member 12345678910 is correct in that a lawsuit will name a number of respondents, including the individual members of the LLC and request access to their personal assets in many cases. However, this doesn't mean they will get them. After all, you can file a lawsuit against anyone for anything anytime. Second, the LLC can provide a tax advantage if you itemize your tax returns. Legitimate business expenses become deductible (unconditionally for a number of years, after which the company must show a profit). This can be done with a Sole Proprietorship company, but the effort of segregating funds becomes more tricky. Third, an LLC, as a business, may be eligible for special banking arrangements at your local branch, loans, credit cards, and discounts with vendors. Finally, an LLC tells yourself to take the work more seriously as a business and others to take you more seriously as a craftsman and a businessman. Don't underestimate the value of this last one.
Not the same as an LLC is what Rhinoknives1 mentions, a company liability policy. You'll need this. And don't let customers or unreliable friends tour your shop or forge (unless they sign a waiver of liability). You don't need that sort of exposure.
LLCs are cheap and easy to set up. The IRS website and your state's Department of State website have lots of information that will help you decide what to do.
Best of luck
Zieg