Is the contest still ongoing? 
My contribution is neither a wall mount nor a custom case, but maybe the idea is helpful to others.
Background story: for future network and setup enhancements (e.g. 24/48 port switch, UPS, etc) and the requirement to keep things tidy and organized (instead of a million devices flying around), I decided to go for a 19 inch rack. However, I did not want to use a “regular” rack due to space constraints.
Solution: a shelf (Ivar) by a “Swedish furniture manufacturer” 
Using the Adam Hall 61535 5U rackstrips the distance between the rack strips’ mounting holes and the shelf’s boards being in the adequate position/height is exactly (to the millimeter) the distance needed for 19 inch rack mount devices.
Result: The shelf with a base area of only 30cm * 49cm and a height of 124cm gives me 2 * 5U with a maximum depth for devices of 40cm (45 if you let them stick out the back).
Note: I have only setup the lower layer so far.
The Omnia rack mount kit I use was mentioned here: Rack mount for original 2016 TO - Omnia HW tweaks - Turris forum