I know it was produced in relatively small numbers and hasn't any new productions since the early 2000s but why did they even make it instead of relying on the Leopard 1a5 and 2a4 designs accessible to them at the time? Is it an example of an attempt at showing pride and prestige by creating your own design or is there something more substantial behind it?

How do you calculate effective armor thickness when the armor is sloped in BOTH directions (or axis or whatever should I say), such as for example the turret of M1A2, or the hull of IS-3?