7 model

Free

RCA / Cinch Y-adapter (stereo to mono downmix for subwoofer)

Printables

Free

Pro-Ject Debut III RCA Box

Printables

Free

Pi3 Recabox Case

Thingiverse

Free

COAX to RCA cable connection box

Printables

Free

Audio Switch Box with Knob (3 Port RCA)

Printables

Free

Audio switch box

Printables

Free

Sony Mega Bass Speaker Boom Box Cabinet - Small

Printables