Would assume that in this case that the gpu was created and assempled using a open blueprint/schematic thats freely available for anyone to see use and modify. Fairly common thing when it comes to stuff like 3d printing where many people freely share their models for others to use.

The joke is in the eye of the beholder, for me it's funny because you have the buzzwords "free and open source" which means you can implement it however you want and the user here decided "fuck it, I will do it by hand".

I don't get it either