My first Diorama card (finished - that is). I played around with the measurements so the card would fit in a standard (4 3/8 x 5 3/4) envelope.
Measurements for front and back are 4 x 7; score at 1 1/2 and 5 1/2. Middle layer is 4 x 5 1/2; score at 3/4 and 4 3/4. The "window" is punched out following instructions in the diorama tutorial by Diana Gibbs (link below) BUT you punch once from the bottom and once from the top giving a larger window.