The nice part about having to print the new pieces was that it allowed for one of the two designs to be altered to provide better protection to the cards when closing the card box. The original design left about 1 inch of the cards exposed above the bottom half of the box. While trying to assemble the smaller/failed box, it occurred to me that the cards could become damaged by catching an edge of the lid of the box on a card while trying to close the box. I wanted to be able to easily remove cards without having to shove my fat fingers into the box, so for the redesigned lower half, I raised the ends of the box to be above the top of the cards. This allows the cards in the middle to be plucked from the side, while providing a safer path for the top half of the box during assembly.

At 9 inches long, by 2.56 inches wide (outside dimensions), both boxes are intended to store a small collection of trading cards that have been sleeved in KMC Hypermat penny sleeves, without much side-to-side movement. The interfacing surfaces were drawn with .0005 [in] clearance per surface, which will essentially be an interference fit if the prints are not reworked post printing.

Wall thickness for non-mating surfaces has been set to .125 [in], and .0625 [in] for mating surfaces. This provides relatively flexible walls in the middle of the box, while the short ends remain rigid. The combination of tightly dimensioned assembly surfaces and the rigidity of either end of the box makes it very difficult for the box to come apart without manually separating the two halves from one another.

Slicing & Print Setup

My general approach to slicing settings is to promote a smooth surface finish, while avoiding settings that will lead to a failed print. As such, I generally do not optimize for print speed or material used. Fortunately, given the surface area of the base of the print, it should have difficult time becoming un-stuck from the build plate, allowing for increased infill and perimeter print speeds. If using the Prusa edition of Slic3r, I recommend reducing the External Perimeter print speed to 18 [mm/s] to support a smoother external surface. I also set infill to 5% with a 3D Honeycomb pattern to provide a uniform pattern/strength to both the bottom and side surfaces requiring infill.

Additionally, to minimize/prevent the corners of the print from lifting away from the build plate, I recommend the use of a 5 [mm] brim. Sharp corners are much more efficient at transferring heat away from a print than flat surfaces. Applying a small brim will increase the surface area of the perimeter of the print, which will help counteract some of the contracting forces as the corners of the box cool.

Post printing