1. Piece of 2x4 or 2x3
2. Wood shims
3. Wood glue
4. 1/2 nails (optional)
Step 1: Glue Wood Shims
1. Glue 2 wood shims together to form a strip of wood.
2. Create 2 strips with 4 shims.
3. Glue the 2 strips across the top of and perpendicular to the 2x4. These will be the base strips.
Step 2: Add Additional Cross Strips
1. Create additional wood strips with shims and glue perpendicular to strips below it.
2. Optionally, reinforce the attachments with 1/2 inch nails.
3. Continue to build up the walls to about 5 or 6 inches high
Step 3: Fill in Gaps
1. On the bottom of the box, there may be gaps with the top of the 2x4.
2. Glue smaller pieces of wood on the bottom to fill the gaps in.
3. Paint the box to make it look clean.