Foglets.

Foglets also known as utility fog is a hypothetical collection of nanobots that can replicate any physical structure such as a human body. The utility fog could be programmed to take on any form from a common house brick to an entire planet. Such diverse choices would make utility fog the ultimate material in construction due to its shape changing capabilities. If necessary the utility fog could program itself if a certain shape wasn't known to exist. I predict that all man made structures will be made out of Foglets making it easier to perform changes without dismantling something such as a house. If someone wanted to turn a car into a suitcase they could do it or if they wanted to create a whole new planet they could. Someone who was made out of Foglets could change their body into any structure they could imagine from trees to axe blades.Too the people of lesser times utility fog would seem like magic because of the mystical applications of the fog. Too give an example of this lets say that someone from the 22nd century traveled back to the 19th century with some utility fog and decided to become a stage magician. If this person was an expert magician with a mastery of the stage (They were a good actor) they could easily trick their audience. Too make it more exiting or realistic they could use the utility fog too achieve some spectacular feats such as turning a table into a lion. The main problem with utility fog is determining whether or not the fog will stop replicating or not too make sure this doesn't happen certain limitations must be put on the replicator. Another problem is the so called Wizards vs Muggles debate,this is a problem that states that someone with sufficiently advanced technology could be compared to a wizard while someone with not so advanced technology could be considered a Muggle.Using this argument we can deduce that someone in command of utility fog would probably end up being considered magical by lesser beings.