well the rack was covered to try to pretty it up a little bit, so you can't see what I did from the front really well so ill try this...

ok here the rack


and here the drawn on one


The black shows the top of the bottom housing and the bottom of the top housing, as you can see there is a space between them

Red shows where the spacer would run, pretend im drawing a 3d image lol. but yea it runs along the sides and back, where the support is, not along the front where there is none and thus keeping weight off the top of the housing below.