During World War II, Germany constructed many armored vehicles using a system of interlocking plates. This is visible at the seams of armored vehicles. The welds are not a straight line, instead the edges of the plates are complementary "teeth" which fit together. This then allowed the teeth to be welded together.
If you look at the following photo of the Jagdpanzer 38, you can see this design along the front of the hull. This particularly design was produced for a while after the end of WWII, but the system of interlocking plates did not appear in any new designs. Why was it not used after World War II?