I've been meaning to set up an airgapped NetBSD 1.6 computer for playing music and writing but am unable to find any packages or source code for programs at the time. archive.netbsd.org only has packages from release 7 onwards.
Look for copies of physical distributions? The Internet Archive has ISOs from 1.5.2: https://archive.org/details/netbsd-1.5.2
Thanks for the advice, found a CD set on eBay for cheap. (The novelty of using CDs again after all this time is worth the price for me!)