I told my wife that but she had no idea of what a 3D printer could do despite having heard people talk about them. So I explained.
A computer lazer printer lays tiny dots of black powder to create the pattern of each single letter. This layer of powder is cooked onto the page by the printer before it comes out of the machine.
Okay, now imagine that a printer lays tiny dots of plastic particles (or even metal) instead of black ink powder, but keeps laying them to build the layers up thicker and thicker. It would not be on a sheet of paper of course, but that is what a 3D printer does, tiny bits built up layer upon layer.
In a few years time you will have the option of buying a mug (because it might be a hand decorated one) or printing one off on your home 3D printer. You will be able to download a variety of patterns (perhaps from your Cloud?) for creating mugs in all sorts of possible shapes and sizes on your home 3D printer.
The domestic size of home 3D printers already exist. See the MakerBot by Thing-O-Matic.
At the moment the home version are only available in kit form from MakerBot and make things out of the same sort of hard plastic that Lego bricks are made from.
I remember listening to a radio programme and I heard Bill Gates saying that some day all homes would have a personal computer. The interviewer sounded unconvinced and Gates said it would be like having a car on the drive, you don;t drive it all the time but it is there for the frequent times you need to use it. He was right.
I predict 3D printers will be someday installed in homes like we have microwaves installed in fitted kitchens.
“The baby has broken his toy.”
“Okay, I will print another. Any preference re colour this time?”
“What did the garage say?”
“They have found out which part failed and have printed another and have fitted it.”
To see some of things people are already printing go to the Thingiverse.