I recently discovered the kaleidoscope card and it has quickly turned into my favourite card design. There are so many ways to embellish this style of card. Layers are cut as follows: 8 1/2 x 5 1/2, 8 x 5 1/2, 7 1/2 x 5 1/2, 7 x 5 1/2. Lightly trace the windows as follows: 8 1/2 x 5 1/2 (2" margin), 8 x 5 1/2 ( 1 1/2" margin), 7 1/2 x 5 1/2 (1 1/4" margin), 7 x 5 1/2 (1" margin). When embellishment is complete, align right edges and pierce a hole, then insert a brad into each corner. Repeat for left hand side of your card. If you wish to mail it, fold your card in half, and then adhere an embellished 8 1/2 x 5 1/2 cardstock to the back of the card. TFL.
More details are on my blog. There is a tutorial for this style of card if you look at my side bar, under tutorials.