Comment by apricot

Sadly, Marcel van Kervinck (one of the two creators of the Gigatron) passed away in 2020. You can still buy PCBs on Tindie, and the parts are easy to procure, it's all standard 74HCT chips. You can find a detailed bill of materials on gigatron.io, and the PCB files are there as well.

The one unavailable part is the fancy wooden box.