Wago 221 Inline 3 Piece Waterproof Connector

A 3 part model that, combined with some M20x1.5 Cable Glands and a snip of 1.75mm TPU filament, you can splice a 3 wire connection together and keep it dry. 

I recommend printing the inner piece with an exterior brim and the caps with an interior brim as all the pieces have some relatively thin edges. No supports are required. 0.2mm layer height, 0.4mm walls. 3 walls and 25% infill. 

Assembly is pretty straight forward; feed each wire through a gland and connector, and add the inner piece to one side. Secure the wagos on to the strands and insert them as pictured (two on the bottom are “upside down” while the single is the opposite). 

Slide and screw everything down, inserting the TPU on the side which has a deeper channel, and tighten up the inner & connectors, then the glands screw into the connectors, then close up the glands around the remaining wire.

Included is the STEP file for high quality import, an STL for those that need it, and the Fusion360 file source if you need to make modification.