I don't have it yet, but the plan is to put some of the silica gel at the bottom the kinda of form a pillow with the felt. That will absorb moisture, I also will do the same at the top of the lid.
Here is a rough draft of the materials used. From what I can remember anyway.
4x24 inch plywood 1/4 inch thick - 1 sheet ( it might have been longer than 24 inches) $4.49
4x12 inch plywood 1/8 inch thick - 3 sheets $1.49 each
1 sheet of green felt with adhesive backing $1.17 each
2 sheets of leather look paper 12x12 inch 1$ on sale
1 package of brass plated hinges $1.49
1 package of brass plated lock $1.49