This cable housing was used to hide the solder connections between a 4 conductor mic cable, and a 2 conductor mic cable (Mogami 2534 to 2549). One half is slightly taller, so you can situate your cables in that one before putting the lid on, which is naturally aligned by the cables themselves.

The internal width of the single path is 5.5 mm, and the two split paths are 5 mm.

Pour epoxy all over the inside and then clamp the two halves together until it cures. I've not had good luck with silicone since it stretches too much.