Took inspiration from ebulldog's model. I actually got that one printed out, and my x4r-sb receiver didn't quite fit in there. The distance between the edge of the PCB that meets the antenna V-block and the antenna ports was too short, resulting in an insufficient bend radius on the wires. Furthermore, the positioning of the antennas on the x4r-sb are not symmetric, and I had to drill out one of the holes to get it to fit. I've resolved both of those issues on this model.
One thing which is lacking, which I don't know if it is a problem or not yet, is the lack of bracing underneath the antennas.
From what I know, this model is compatible with: x4r, x4r-sb, d4r-ii
Designed in FreeCAD v0.16