When I was regularly doing stuff on a beta machine I was making quite a few boxes and storage items. I searched for a while and found nothing that did what you are describing.
My fallback is just to use a box maker and edit the files. In general what you want to do is similar to the path I followed here: Beta day - five (Fitted Gauge Box) only I was making a horizontal divider instead of a vertical one.
Most software falls into one of two camps. Either it is easy and specific and thus limited to one purpose (i.e. box making) or generalized and complex with an ever increasing set of functions. Pick one of the latter and learn it well, then you can solve generalized problems. If what you want is something very specific and simple that no one else is doing, you might have to make it yourself!