Inserts are standard scrapbook sheets, 12 x 12 inches, and I spaced rhe binder posts at the standard '3 hole' spacing so I could use a standard 3-hole punch.
You can buy a standard wood scrapbook cover from Michael's but I chose to make my own of maple plywood. Stained with golden oak stain and several coats of satin spray lacquer. The overlay is 1/8" baltic birch and the small 'hummers' are 1/8" walnut.
It was a joy to make!!!
~~~GB~~~