WOW, they are beautiful boxes as I haven't seen any octagon boxes. I love how you trimmed them out and the quilting you did as well.

I made 11 of them last year for Christmas gifts...used warm and natural for the batting and heavy, iron-on interfacing on the lining. My son piles a lot of things in his and it's still standing perfectly straight. Started off with a 10" square which yielded somewhere around a 4 1/2" to 5" square box.

I haven't made the octagonal boxes but have made many fabric boxes as gifts last year. Used a 12" square to start out.

I use the stitch to attach buttons to tack down the corners and I try to find buttons I like that I can also attach with my machine. Usually I can make the whole fabric box on the machine - no hand stitching. Made one for each month for my sister-in-law this year and also ones using Ohio State fabric for my MIL. I put wrapped candy in the ones I give for gifts.

There are some tutorials on this Board for these.

I always send my daughter Wisconsin cheese for Christmas. Last year I put them in fabric boxes made out of Christmas fabric. She is 28 and loved them (and the cheese). The cube shape of the cheese blocks kept the boxes nice and square during shipment and also provided a little insulation- she lives in Florida.