The company's competitive advantage is its engineering expertise, and that's a relevant edge even with additive manufacturing. Someone's still gotta design the product blueprints that get fed into the computer, after all.
Way I see it, the real threat is to the company's component products segment - after all, if you use additive manufacturing to build the whole widget from the inside out, there's no need to contract out to a company like UFP to make components for you. But that's not going to be a problem until the new technology becomes cost efficient enough to become the dominant form of manufacturing, and that's probably at least a decade or two away. By which point UFP could be looking like an entirely different company. This company is nothing if not adaptable.
In short, it's something worth paying attention to, but not a reason to sell or refrain from buying the stock, especially at these prices we're seeing right now. Just some thoughts. :)
Additive manufacturing may eventually become economically competitive for certain high-end and/or low-volume applications. However, UFP Technologies is not in that niche. They make low-end high-volume packaging.