The junction boxes needed to be exactly the right size, and they needed to be made from a specific plastic so that i could get them chromed at a later stage. I ended up importing the boxes because i couldn't find exactly what i wanted locally. These are the boxes i used:

Holes made and some shower hose fitted for testing:

After some chroming and lots of wiring, this is what the wiring looks like inside the first junction box:

Here the ATX cables were routed throught the shower hose:

The final result: