Just a quick mash-up to allow the bins to be joined in multiples without a side panel. There are two versions, one with the notches removed from the original part and one with the side panel added under the original part. The second one should play well with the original bins (i.e. line up for stacking)
Print one less than the width you desire, then print one original bin and one side panel for the ends and multiple hooks from the original source: http://www.thingiverse.com/thing:9136
For bins that you want to remove and stack, print the original parts.