Cloudprinting, Withdrawing Plastic, and Water-jet vs Laser

Today I Learned:
1) There's a thing called "cloudprinting" (not to be mistaken with cloud printing, which is a network printer) where you make floating shapes out of foamy bubbles. It's easier to show than to explain: http://ift.tt/1JHxbw2

2) When 3D printers print (at least, when ours prints), they force out the plastic as they print, then withdraw the plastic inside the nozzle a little when they move from print site to print site. I'm not sure why they withdraw the plastic, but I suspect it has something to do with not trailing little bits of print material around.

3) Water-jet cutters are better than laser cutters because they're more powerful (a water jet cutter can cut through steel, easily). Laser cutters are better than water-jet cutters because a) they can engrave things (water-jet utters are too powerful) and b) they are more precise.