The Mark 3 is still a work in progress. The original thread about it can be found here:
https://groupdiy.com/index.php?topic=55613.msg709792#msg709792
I just realised the first post was in March 2014 so it has been going for six years. The reason it is taking so long is because it is quite a challenge squeezing tubes into a 35mm wide module plus the fact it keeps being interrupted while I build mixers and other stuff for people. In the process I have developed a new mechanical sytem and designed or commissioned several transformers not to mention quite a few PCBs.
At the moment the plan is to build the "8 Tracker" which has a channel strip with mic, line and tape inputs as well as direct outs, four groups and four auxes. The standard cheek is 12 modules wide so 8 will be channel strips and the remaining four will be the master section. I intend to build this mixer complete and the sell it.
I will also make the PCBs available as with all my projects. The cheeks were designed by SRS here in the UK. They will be able to supply you with a set along with all the necessary extrusions, card guides and fixing hardware.
Cheers
Ian