Sadly, the APS film format is no more.  It was a sub-35mm size format in cartriges that also contained the film AFTER processing.  You dropped off the film for processing, and then got it back in the same cartrige for long term storage.  Extremely convenient.  The film came in elliptical plastic containers with snap-on caps.  The volume was a bit smaller than the 35mm cannisters, but the caps were squared off!  As you can see from my photos, it makes for easy registration both with the tubing setup, and the installation.  Go to your local film processors ( if any, remember them??) and ask if they have any of the containers.  Probably not a bad plan to grab all the 35mm cannisters while they exist, too.

If anyone comes accross a treasure trove of these APS containers, let us know!  Pity we didn't know we needed them while they were plentiful.  Probably most of them are in landfills or have been recycled by now.