Retractable Knife Sheaths

As the summary put it so plainly, knives need to be made with sheaths that can retract into the handle. These knives would appear to be just long, multi-layered boxes. However, push a button on the side and the cover on the blade retracts somehow into the handle, leaving it free for use. The button could even have a safety latch of some sort to keep children from being able to use it. Also, the top end could be covered with some sort of flexible foarm or rubber with a tiny slit in the middle for the blade to slip through. This way there is no hole at the top to stick fingers in and get cut. This is safer then switchblades because the blade is not extending out of something; it is simply being revealed. The push of the button does not lengthen the possible weapon but opens it up for use.

It would be useful mostly as a safety measure for children who can pull most kitchen knives easily out of their sheaths if they can get to them. With a retracto-sheath, you can even hand a covered knife to your child, tell him to run it over to daddy, and have no fear of him tripping and cutting himself (not that we should encourage children to run with knives even if they are sheathed).