Cut card base 8 1/2 x 4 1/4 inches Score at 2 1/8 inches from either end.
Mark 1 inch on either side of the score line and 1 inch along the score line. Score between the marks.
I have found that using a ruler and the bone folder is a simple way to make the diagonal score lines.Repeat with other square pieces.
Fold in the sides to be sure the pieces are correctly placed.
Place the center octagon and side half octagons as desired. Again the center pieces is not a perfect octagon so you may need to play with it a little to be sure you have it placed correctly. The border around the pieces may not be exact as a very tiny discrepancy when making the 1 inch marks or cutting the diagonals can make a big difference. Most recipients will nto notice that - so don't fret over it.
Add the other half octagon pieces to the card front.
Fold up the card to make sure everything works together.
To make the belly band, cut a 1 inch x 11 inch strip of card stock.
Placed the closed octagon card near the center.
Loosely wrap the strip around the closed octagon - it should fit but not be so snug you can't slide it off.
Decorate as desired.
I have made this without attaching the 4 squares and it is also an impressive card.

This card does not have the squares and I placed an image in the center,
so I cut a neutral octagon to place on the back for writing a greeting and signing the card.