Read an article about latest inventions and put the parts of the sentences below into the gaps.

Write one letter in each gap.

3D printer

A 3D printer is one of the most useful and unusual inventions that we have ever had. It's [ ]. This device is primarily associated with simple, home-made plastic items. But the number of areas in which it is already applied or can be useful is overwhelming. 3D printers help engineers make designs, reducing time and costs. Useful and small items can be printed on it at home. In some industries, especially small-scale ones, the production of parts on 3D printers will be cheaper than on classic lines. Even in making food, growing organs, and creating medicine, this technology can be useful. And fans of stories about robots that capture the world will be interested to know that there are models that can print more than half of the details for themselves.

Holograms

Many people remember scenes from science fiction films where a conversation is conducted with a hologram of a person, creating the full effect of their presence in the room. Well, it is already possible to reproduce a sufficiently high-quality image on stage. One of the most famous examples of this is a hologram of a celebrity who died many years ago. And Japanese performer Hatsune Miku is generally a completely artificial star who gives real concerts. The first prototypes are presented, giving 3D images of not very high quality. You can even interact with them using your hands. The [ ] has not been completed yet. It is still in progress because it's not easy to transmit the sound and the image at the same time. That's why developers have been working on it for a long time. It can [ ] it.

A. development of this technology

B. a marvel for the

C. even take decades to complete

D. and small items can be printed on them