While most three-dimensional printers are put to work making small parts or prototypes, start-ups are developing techniques to make much larger things, including houses and rockets. Construction technology company Icon and housing nonprofit New Story used a large-format printer to build the concrete foundation and walls of a small, 32.5-m2house in Austin, Texas. The house was constructed in 48 hours at a cost of about $10,000. Icon says it aims to build houses of up to 75 m2 and to refine the process to make it faster and more affordable. While its first mission is to build affordable housing in developing regions, Icon says its printers could also be used to make habitats in space. Icon’s 3-D house printer could someday catch a ride on a 3-D-printed rocket made by another start-up, Relativity Space. The company raised $35 million in a second round of funding led by venture fund Playground Capital. Relativity says it has built the world’s largest 3-D metal printer, which it plans to use to make inexpensive rockets that can carry large payloads, including car-sized satellites.