The following sources were cited in SAP Digital Futures Issue 34: 4D Printing: Self-Assemble, Self-Shape, Self-Repair.

The global 4D-printing market is expected to reach US$64.5 million by 2019 and increase at a 33.2% CAGR through 2025.
14D Printing Market Analysis by Material (Programmable Carbon Fiber, Programmable Wood, Programmable Textiles), by End-Use (Defense, Aerospace, Automotive, Textile, Healthcare), by Region, and Segment Forecasts, 2018–2025, Grand View Research, June 2017, https://www.grandviewresearch.com/industry-analysis/4d-printing-market.

The market for various programmable materials, which are the foundation of 3D printing, are expected to grow at a CAGR of 20% or more through 2025.
24D Printing Market Analysis by Material (Programmable Carbon Fiber, Programmable Wood, Programmable Textiles), by End-Use (Defense, Aerospace, Automotive, Textile, Healthcare), by Region, and Segment Forecasts, 2018–2025, Grand View Research, June 2017, https://www.grandviewresearch.com/industry-analysis/4d-printing-market.

MIT’s Self-Assembly Laboratory first developed the technique in partnership with Stratasys and Autodesk, but researchers around the globe are developing new use cases.
3“4D Printing,” Self-Assembly Lab, https://selfassemblylab.mit.edu/4d-printing/.

Current demand is strongest in the defense, aerospace, automotive, and healthcare industries.
43D Printing (3DP) Market Worth $23.79 Billion By 2025 | CAGR: 16.5%, Grand View Research, October 2018, https://www.grandviewresearch.com/press-release/global-3d-printing-market.

NASA’s flexible metal “space chain mail,” which could be used to shield a spacecraft from meteorites, for astronaut spacesuits, or for capturing objects on the surface of other planets
5Elizabeth Landau, “‘Space Fabric’ Links Fashion and Engineering,” Jet Propulsion Laboratory, California Institute of Technology, April 18, 2017, https://www.jpl.nasa.gov/news/news.php?feature=6816.

A self-assembling shoe that could eliminate a complex production process involving significant labor
6D.J. Pangburn, “MIT’s Future Shoe Can Transform Itself,” Vice, November 2, 2015, https://www.vice.com/en_us/article/4xq78b/mits-future-shoe-can-transform-itself.

A 4D-printed airway splint that grows with the child for infants suffering from a condition that causes their windpipes to collapse
7“Medical Technology: ‘4D Printing’ Adds Breathing Space,” Financial Timeshttps://www.ft.com/content/7b6af16e-f362-11e4-8141-00144feab7de.

Airbus’s air inlet component, which is made of programmable carbon fiber that adjust itself automatically to control airflow used to cool the engine, removing the need for heavy mechanical control systems
8“4D Printing and Digital Materials,” Airbus, March 23, 2016, https://www.airbus.com/newsroom/news/en/2016/03/digital-materials.html.