I was in a hurry to test a wiring setup using a Raspberry Pi 3A+, PCM5102 DAC, and stereo output. A quick search on Printables led me to the original model. That is basically a ventilated baseplate & side which saved me designing a suitable base. 

With OpenSCAD I added the posts with 2mm screw holes to mount the Pi 3A+ and the vertical side-plate with cut-outs to fit the RCA stereo sockets (cheap from AliExpress). These sockets are spaced 14mm between centres, and the 3mm screw holes are also 14mm between centres.

The model file “3A+ Mount for DAC + RCA plugs.stl” will make what you see in the photo of the working mount.

If you want to alter the OpenSCAD code, you will need the file “3a_mount.stl” (the original baseplate) in the same folder as the .scad file. All the parameters are named so alterations should be straightforward.

And the sound coming from the PCM5102 is remarkably good for such a cheap product from AliExpress!