A friend is making some Japanese tool boxes for his grandkids (I did a show and tell of these at the May club meeting). I suggested he use wood 1/2-5/8" thick to keep them from getting two heavy. I also suggested the following method that I've used before to get good wood. I buy 2x10 or 2x12 Southern Yellow Pine (SYP) meant for joists. It is relatively knot free. And if you get some with the pith down the middle you can saw out an inch or so and get perfect quarter-sawn lumber. Then you re-saw and you get wood just a fraction less than 3/4" that you plane down to desire dimension. Over time SYP gets as hard as oak. He came over yesterday and we planed down the sawn and factory surfaces. He's edge-gluing them today and I think they'll look great when done. If you've never seen one, they are pretty neat. The top slides one way to open and the other to close securely. Then end cleats make handles.