I always wanted to build a custom intake for the old 2.2L 8V in the Z but when it expired and I decided to put the 2.4L in the car, I ended up making my first custom intake manifold for it back in 2007.
It is a basic box plenum design, end loaded and with raised velocity stack ports. Not what I would call perfect but a balancing act (as usual) between function and packaging space.
OK, "Why raised runners?"
A fluid (air is a fluid) flowing in a tube (or box shaped channel) has its highest velocity in the center of a tube and slowest at the perimeter boundary layer (read: outer walls) and worst in corners if the tube has a rectangular cross section. Raised velocity stacks help pull from the higher velocity center stream as opposed to the somewhat stagnant boundary layer.
Additionally, due to packaging constraints, using raised stacks allowed me to get a little longer runner so it was a double bonus.
Well enough words, here are some pics of how I made it...