Assembly comprising at least two separate portions, such as a suitcase with lid, a vehicle with doors or the like

An assembly comprising:

• a first polygonal part and a second polygonal part, the first and second parts being engaged against each other in a closed position for the assembly;
• the first and second parts each having at least two non-parallel sides connected to each other at a corner and extending at an angle to each other, each side having a rabbet edge and the rabbet edges of said first part being shaped to closely engage the rabbet edges of said second part in the closed position;
• the edges of each side having a gently undulating profile with at least one arc on each side, one of said parts having convex arcs which correspond to, and closely engage concave arcs of the other of said parts;
• and
• the corners being rounded and one of the concave arcs of one of the parts extending around the corner thereof and being closely engaged by one of the convex arcs of the other of said parts which extends around the corner of the other of said parts.