Some of the qualities that I would like in a material to create a self replicating structure/habitat are: strong, durable, light, and flexibile. It would also be good if it could self repair, and was "self-aware" ie, that it had some means of checking its own conditions and changing its behaviour based on those conditions. For example, it could tell how much tension it was under, or that it needed to be repaired. Another possibility would be a material that could chemically attatch to more of itself. For example, a sring that was capable of attatching to another piece of the same string by merging with it, rather than tying together. This would allow self replication and repair from a molecular level, especially if multiple such materials were combined, each having different properties, to create a more ideal material. It seems to me that textiles are and ideal way to go for manucfacturing. Depending on what materials are chosen, and how they are woven and combined, one can get almost any function that they desire. Nylon, mylar, carbon fiber, cholorprene, aramid-fiber, neoprene, polyester, resin, and other materials have already been combined to meet just about any need. The problem with textiles is that have to be woven, and are difficult to repair once they are broken, and usually do not have the same strength once repaired. However, textiles are more a means of manufacture than materials in and of themselves.
Two things being widely investigated for strength, flexibilty, and durability are spider silk and carbon nano-tubes. Carbon nano-tubes have been shown to be usable for just about every conceivable situation, but manufacturing large lengths is also difficult. Spider silk is a protein based compound which has proven almost impossible to manufatcture, but it has been used naturally as fishing line, bags, clothing, amongst other things, dpending on the silk used. Supposedly, a pencil thick strand of silk could stop a Boeing 757. The silk also can stretch 30-40%, much more than steel (8%), or even nylon (20%) Some spiders are able to redigest their own silk and reuse it. The thougght occurs to use spiders, or some component of then as part of a self replicating structure, which leads to the topic of using a cellular organisms in materials or as part of the habitat, probably with some sort of physical or genetic modification.
Genetic modificatin and engineering seem to offer us limitless possibilities to make use of natures work to create living things that are designed to do a specific job. From bacteria tailored to digest certain materials for cleanup purposes to livestock that produce vaccines, from glowing green bunnies to spider-silk factories, and from genetically modified super-warriors to specially tailored mega-viruses. With the power to do good come s the power to do harm as well. While on the one hand great things can be done, on the other hand we know so little of how what we are doing with genes will impact things in the future, are moving so quickly, and have so little oversight and control over the spread of genetically modified organisms, that one has to but a choke on the process. Another problem is the patenting of genes that have been discovered by different companies, genes that make up our race, what we are. Should someone be allowed to patent a gene, should we be allowed to modify other organisms to fit our needs and pleasures? The process of gentetic engineering must be slowed down, given more time to experiment and observe results to ensure safety, and combined with a thorough investigation of natural systems, both within and between organisms, in order to get a better understanding of what has been done, what can be done, and how things effect each other in nature, so that we can safely use that knowledge in the future to our advantage.