The Gigatron TTL computer is now fully open source! The source code had been open source (BSD license) since the beginning of course. A while ago, we published the design files for the printed circuit boards, both for the Gigatron and for Pluggy McPlugface, the PS/2 adapter.
We have now also made the full Assembly and User manual available online, under a CC-BY-SA license. The assembly manual contains the list of components, which is now also available separately as a Bill of Materials under the same license.
These files should enable to you make your own Gigatron. The only part that is no longer available is the custom made wooden enclosure.
If you decide to build your own Gigatron, we won't provide support. But we do encourage people to go down the rabbit hole :-)