1. Castle Island Worldwide Guide to Rapid Prototyping - directory, tutorials, comparisons of technology, systems for less than $20K, by Ed Grenda
2. TCT online - rapid product development and manufacturing news, resources, by Rapid News Publications, UK
3. Make Parts Fast - online resource with articles, print supplement to Design World Magazine, sent to 40,000 readers, managed by Leslie Langnau
4. 3ders.org - compare printers, materials, news
5. 3DPrintingIndustry.com - articles, blog posts, opinions, videos, images, by Rachel Park
6. 3dPrinting.com - news, articles by Robert Dehue
7. Rapid Today - directory of service bureaus, forum, resources, by Rapid Publishing
8. The Rapid Prototyping Homepage - massive page of links to commercial RP systems, resellers, service bureaus, consultants, publications, associations and academic resources
9. Rapid Prototyping - entry in Wikipedia, the free encyclopedia
10. Wohlers Associates - articles and reports written by RP industry leader Terry Wohlers, plus links to other RP resources

Recommended

• SME's Additive Manufacturing Community - news, books and tutorials (for purchase), article reprints, resources, by Society of Manufacturing Engineers
• RAPID Conference & Exposition - annual trade show by Society of Manufacturing Engineers
• Rapid Prototyping Electronic Mailing List - boasts more than 1,500 subscribers and offers an edited and categorized archives of messages that to download
• Rapid Prototyping Journal - research publication on additive manufacturing, 3D printing, by Emerald Publishing
• RTejournal - online magazine, articles on additive manufacturing, German and English
• Virtual and Physical Protoyping - quarterly publication, scientific and academic, by Taylor & Francis
• Rapid Prototyping: An Overview - one page summary plus links to various RP technologies for more information, by efunda