A container including a first panel with a first edge having a first protrusion with a first contoured profile with at least one projection, a second panel with a second edge having a second protrusion with a second contoured profile with at least one projection, and a spline with a first channel that defines a recess with an interior profile, and a second channel separate from the first channel that defines a recess with an interior profile. The first and second channels receive the first and second protrusions, respectively, such that the first contoured profile is complementary to a portion of the interior profile and the second contoured profile is complementary to a portion of the interior profile. The first and second panel include a mid-section extending from the first and second edges, respectively. The first and second edges have a greater thickness than the thickness of the mid-sections.