I really like Systematic (REALLY), but was curious about how custom themes worked, so I decided to try to do something quick. This is the result:
There are many things that can be improved (removing small text, first of all, and there are some inconsistencies), but I was pretty satisfied. Using only the logos, without a frame would make me go crazy.
Of course after this I went back to Systematic.
Edit: sorted most of the problems I had with it and uploaded them here: