I don't recall the exact date that the XGP showed up at MIT's Project Mac, but I think it was the very early 1970's. The XGP was the first bitmapped XeroGraphic Printer, and it changed the course of printing history, including leading inevitably to the Apple Macintosh/desktop publishing industry and the now ubiquitous "multifunction printer/scanner/fax" that probably all of you have in your homes. The coolest thing about the XGP is that it was available to (nearly) anyone at 545 Tech Square, and it immediately became a huge hit. Once the appropriate page layout languages and fonts became available, people twiddled with them incessantly, until their theses looked like ransom notes! One of the important steps along the way was the development of Knuth's TeX, which subsequently became the standard for mathematical publishing -- where it remains today. --- Fast forward to 2011. 3D printers exist, but don't appear to have generated the same excitement as the original XGP. I'm not sure quite why, because a 3D printer is sooo much cooler than the XGP ever was. Maybe these printers are too expensive; maybe they're too slow; maybe they're too hard to access. What is missing that would make the 3D printer today as exciting as the XGP was in the early 1970's ? Does Knuth (or a Knuth-wannabe) have to come up with 3D TeX ? What do mathematicians want from a 3D printer, anyway ? What would be the effect of putting a free 3D printer into 100 universities ? 1,000 universities ? 5,000 high schools ? 10,000 grade schools ? 50,000 libraries ? (I have no connection with any 3D printer company, but think that it is a major revolution.)