The following sources were cited in SAP Digital Futures Issue 04: Makers Shake Up Manufacturing

The 3D printing market will quadruple to US$12 billion by 2025.
“3D Printing Market to Quadruple to $12 Billion in 2025” [press release], Lux Research, April 29, 2014, http://www.luxresearchinc.com/news-and-events/press-releases/read/3d-printing-market-quadruple-12-billion-2025

In 2006 the San Francisco MakerFaire attracted 65,000 enthusiasts. Last year 130,000 attended, and another 85,000 attended in New York.
Maker Faire: A Bit of History,” MakerFaire.com, accessed August 11, 2015, http://makerfaire.com/makerfairehistory/

“Media Kit & Press Resources,” MakerFaire.com, accessed August 11, 2015, http://makerfaire.com/media-kit-press-resources/

Today, there are 1,100 hackerspaces around the world giving people access to production tools once available only to corporations.
“List of Hacker Spaces,” hackerpaces.org, accessed August 11, 2015, https://wiki.hackerspaces.org/List_of_Hacker_Spaces

Peer-to-peer e-commerce site Etsy’s revenue nearly quadrupled in only 4 years − from US$525 million in 2011 to US$1.9 billion in 2014.
Ruth Reader, “Etsy Starts Trading on the Nasdaq at $31 per Share — Nearly Double Its Original Price,” VentureBeat, April 16, 2015, http://venturebeat.com/2015/04/16/etsy-starts-trading-on-the-nasdaq-at-31-per-share-nearly-double-its-original-price/

Crowdfunding campaigns generated US$11.08 billion in 2014. The market will grow to US$93 billion by 2025.
Katie Kuehner-Hebert, “Crowdfunding Volumes Grow to $16B”, CFO.com, April 2, 2015, http://ww2.cfo.com/credit-capital/2015/04/crowdfunding-volumes-grow-16b/

Crowdfunding’s Potential for the Developing World (Washington, DC: infoDev, Finance and Private Sector Development Department, The World Bank, 2013), http://www.infodev.org/infodev-files/wb_crowdfundingreport-v12.pdf