indeed home made guns have a very long history. the serious gun violence that they fuel in Papua New Guinea has been known about for years.

extremely detailed paper: http://www.smallarmssurvey.org/fileadmin/docs/B-Occasional-p...

for something a little less dry and with pics of the guns see: http://www.vice.com/read/port-moresbys-little-raskols

the 3d printer angle is interesting from a tec perspective, but i cant help feel that this is more about a guy building himself in to the linus of guns then gun policy.