The Unirack 19 II from RME is designed for rack mounting non-19" (half) units like the RME Multiface, Multiface II, Quadmic, ADI-2, Fireface 400, ADI-4DD and many other units into standard 19" rack mounts.
The 1U shelf features multiple drill-hole positions, and oblong slits on the back are designed to be used as cable strain-relievers.
Links to unit models:
