Custom media shelve spacing

when building your custom media shelving what do you guys use for spacing of the shelves? When I originally built mine I used the Disney Clamshell VHS cases for spacing of my shelves but know some of my DVDs are larger then those clamshells. So now I was planning on using my Evil Dead II: Dead by Dawn Limited Tin for the spacing but I have a feeling that after a couple of months I may find something larger once again.