Check out the total rack space size of your equipment to be mounted.
1 rack space equals 1.75 inches ( A 2 space amp or effect = 3.5 inches etc.).
You can place/line up your equipment on a table measure the total distance in inches and divide by 1.75 to get the size of RACK needed for your rig.
you may want to add a few extra spaces to leave room to add other items later on.
check out the different racks available:
http://marathonpro.com/cases1.html