for looks only ... just make a cable with a 4-pin molex (PC) connector and leave the other end bare. (just use two wires instead of the normal four ... one for the yellow and one for ground)
... then use female fully insulated quick disconnects and make the necessary connections.
just like you wired the grounds on your buttons and joysticks .... daisey chain them ... all the yellows to the 12V items .... well you get the point .... and every device just loves a ground

or if this is easy to understand ... just make a daisey chain for your 12V leads ... and one for the grounds ... then attach the 12V chain to the 12V line coming from the PSU and the same goes for the ground.
if I only owned a digital camara ... hehe ... I'd post step by step pictures pictures because I'm a computer builder by trade and have tons of this stuff to demonstrate with
