From Live Science:
Invisibility cloaks made of plastic can now be created at home using 3D printers, researchers show.
The first clues that cloaking devices might one day become more than science fiction, a la "Star Trek" began emerging seven or so years ago. Since then researchers have made such cloaks a reality by smoothly guiding rays of electromagnetic radiation such as microwave beams completely around objects so they proceed along their original trajectory as if nothing were there.
The first working invisibility cloaks were demonstrated using complex lab experiments. They can now, in principle, get made at home using 3D printers.
... The cloaks have open spots in their centers in which to place items up to 5.5 inches wide (14 cm). When microwaves are beamed at those objects from the side, the cloaks make it look as if the items are not there.
"A metal cylinder that would normally reflect a lot of microwave radiation can, once placed in the cloak, become transparent to microwaves," Urzhumov said.
Cloaks that make objects invisible to microwaves could have military and civilian applications.
"If you want to eliminate obstacles such as pillars or small buildings to microwave antennas, you could use these cloaks, which could be helpful for communications and for radar," Urzhumov said.
The fact that invisibility cloaks now can be made with pushes of a few buttons also makes it much easier to experiment with them. "We can try many different variations and optimize them, look for the most efficient versions," Urzhumov said.
So far, these cloaks hide objects only when viewed from the side. "We would like to make cloaks that render objects invisible to beams coming from any direction, fully 3D cloaks," Urzhumov said. "This would involve gluing together several cloaks to form a larger structure that completely encloses an object."
Much larger cloaks are possible in theory.