It's the biggest such sales decline in several years. 3D Systems closed trading Wednesday at 14.54, down 0.8%. Stratasys and 3D Systems face increased competition from giants such as General Electric ( GE ), HP Inc. ( HPQ ) and others. Stratasys and 3D Systems are the largest 3D printer makers by revenue, but both have found demand failing to live up to the early hype of a 3D print revolution. The 3D print trade faces an array of challenges, ranging from the type and price of potential materials, to rethinking entire supply chains for portions of the industrial landscape. HP made its long-awaited entry into the 3D printer market 15 months ago. General Electric last year purchased two European 3D printing companies, and has developed jet engine technology via 3D printing. Boeing ( BA ) has used the technology, also known as additive manufacturing, to make tools and parts.