Top and Bottom design for the Box
Let's get the bottom out of the way first! If the box is going to be 9x12 or smaller, I generally use 1/8" plywood for the bottom. Most jewelry boxes or humidors will not contain enough weight to distort the plywood. Plywood with a variety of veneers on one side are available, I choose something compatible with the wood in the sides of the box, the grain of the ply, must, of course, run with the length-wise dimension of the box. I have a personal brand that goes onto all of my work, and I apply it now to the veneered face- rather than risk ruining the project after the bottom is installed permanently in the assembled box.
We need a groove to fit the bottom into, a saw cut made with a thin kerf blade (3/32") will suffice. I usually make the rebate 3/8" deep and 1/8" from the bottom edge of the box sides. If you are nervous about having the blade this close to the fence, a temporary board could be clamped to the face of the fence.
One other consideration might be, that, if you were planning any sort of decorative cuts around the edges- you might have to relocate the grooves or modify their depth. Our bottom needs to be diminsioned to fit with about 1/16" clearance in the groove on the assembled box. Whatever lining you install later will cover the plain (in)side of our plywood.
Fitting a Top
Several basic box styles could be; a flat plywood top with veneer cemented to each surface; a flat piece of wood; or, a raised panel style top. Let's leave out the veneering for now, it's a tough job for a less experienced woodworker to do well. We could use a flat, thinner board for a top, thinner means that it might be 1/4 to 1/2" thick and fittted in a rebate similar to the bottom. An essential concept here is that whatever material is used for the Top and bottom, it must not be glued in place. The reason being that the sides will have their grain running at right angles to the end grain of the top, since wood will always swell and shrink with seasonal variations, the wood must be free to move a bit, our book store offers texts that expand on this subject at greater length.
A flat panel of the diminsions discussed above will need to be planed to the appropriate thickness, The top could be of the same lumber as that sides or of a contrasting wood, i.e. A walnut top with cherry sides. Choose the wood here with the same care as in locating the best part for the front side of the box.
The rebate to recieve the top must be sized with care; the lid should be "just" free to move. I prefer to cut the groove with an adjustable dado head; a router mounted in a table could also be used; lacking these, a groove could be achieved by making several overlapping cuts with your regular table saw blade.
Whatever top is decided upon, I prefer to finish sand and apply a coat of my finish before glue-up, since your top will be able to move in a limited way, it is important to have finish on the edges inside the rebate, this also prevents stray glue from adhering to the top.
Another great idea would be to resaw a narrower board that you like and edge-glue the sections together in what is called bookmatch style. After the board is resawn, the halves are opened like pages in a book and glued, beautiful effects can be achieved this way, and you do not need a real wide board to create your top. You will want to make yourself a taller fence to keep your board vertical while reswing it. These boaeds need careful clamping to maintain their flatness abnd to get a nice joint (this joint will be very visible). Since the grain pattern will not match perfectly after you cut the board in half, your original board should be a little long to allow you to slide the boards to arrange the best effect in the bookmatch. After gluing, you will need a planer to flatten the wood or to use a belt sander with finer grits to level the surface. The groove should not be cut in the sides until your top is done, allowing you to make the rebate a correct width.
Raised Panel Tops
Raised panel tops are very traditional and lend an air of formality to a box. The general idea of a raised panel can be seen in the illustration at the right. There are a variety of designs for the edges of the panel, shown is a cove. These are generally made with a table mounted router, a couple of designs can be achieved with only a table saw. there generally would be some treatment of the sides to create coves, ogees or bevels to enhance the box. The grooves for the top will need to be located so that "iland" of the top is level with the top edge of the sides. Now and then, I manage to get the groove a bit too loose for the top, and, then I add bits of very thin weather stripping in the bottom of the grooves. This can center the lid and still allow for seasonal changes in the wood.
Now, it's time to get out that "giant rubber band" that we made earlier, and, dry fit the entire box together.
Detail of Raised Panel Top