Few things need to clarify.
First, Canon 5Dmk3 (also include 5DS,5DSR,7D,5D2) are all using "Compact Flash" which is a type of SSD based on the IDE interface.
However Canon C200 uses "CFast 2.0" which is a type of SSD based on the SATA interface (which we used a lot on our computer nowadays)
In the same time, the socket they developed is also based on the SATA. As in the video send by gzillarocks, there is no chip set in between the socket and the mSATA.
The highest speed IDE socket can go is around 133m/s while SATA2.0 can support around 300m/s. Not to mention SATA3.0. SATA and IDE conversion need a chip set, not simply putting wires together. That is the reason why no one makes the adapter on the market since there is only a little demand on this. (Hey, professional cinema cameras are all have CF2.0 or even USB type-C installed

There is no Adapter on the market have the function we need, so we have to make our own

I am only an undergraduate freshman majors on EE, no experience on making the PCB. But lets see how far we can get on this since I think it will work theoretically.
PS:Compact Flash can also being known as IDE 50(since there are 50 pins on it), I saw these kind of SSD before when my father was still using floppy. They have the exactly the same socket as compact flash do, just little bit longer and wider on the body. But people are not manufacture these drives anymore and because of the high selling price at that time, these kind of dives didn't sold a lot. So it is also hard to be finding in the second-hand market.
