Stackable, interlocking containers for small items

Here we have interlocking containers that can be arranged and stacked to organize parts, medicines, supplies, etc.  For example, a tray 7 columns by 3 rows could organize AM, midday, and PM medicines for the week.  Common uses include organizing fasteners, small parts, and sewing supplies.

Each stacked layer serves as the lid to the layer below.  Thus, you only need to print lids for the top layer(s).  Unlike drawer style organizers, the material redundancy of an outer shell with an inner drawer is eliminated, and you are not constrained to a single layer of storage.   The rectangular stacks fit better on shelves and in drawers than hexagonal shapes.

The prototypes have only been printed with PETG at the 0.2mm, speed setting.   Supports are not needed.  Higher quality light-colored filaments that are not stringy are recommended.  It takes some coordinated force to interlock multiple rows and there is some flexing of the walls during locking.   PLA might not be able to handle the flexing.  Small cuts in the dovetail geometry ease a pivoting, rotating move in one direction more than the other when interlocking groups of containers.  

After printing, before assembly, file off any stringiness, and crisp up square edges as needed.  Check the proper mating of all sides of a block one face at a time - each single face should be very easy to lock or unlock against another single face, and very easy to stack with another container.  When multiple rows are joined, the unlock motions are opposed by the locked joints so the containers do not come apart except by using firm deliberate, properly directed force.

Two sizes of containers are provided - 45mmX45mm  and 55mmX55mm outside dimensions with inside depths of 15mm and 25mm.