1/4" Pine plywood. You can use whatever type of wood you want, but pine looks nice and is relatively cheap.
You'll need enough wood to cut out the following pieces:
Two 5.5" x 10.5" pieces
One 8" x 10.5" base piece
Two 8.5 x 5.5" pieces
Five 2 7/16" x 11" slats
Also you will need two 6 sided half a decagon pieces. This sounds confusing but I've included a template to cut these pieces out. Print the template out and cut the pieces to be 8" wide at the base.
You'll also need:
Black poster board
A cheap mp3 player
Treasure chest opening mp3
Solder and flux
Some small gauge wire (20 or 22 gauge will work)
SPDT lever switch from radio shack
Small audio amp. I used a cheap ipod speaker amp from the pharmacy.
Enough Black felt to line the inside of the chest, about eight 8 1/2" x 11" sheets.
150 black furniture nails.
Long straight edge
A couple black sharpie markers.
Hot glue gun
Minwax Red Oak woodstain
Brush to apply stain with
Pliers or wire cutters
A couple of hinges.
A means to cut your wood. (Radial arm saw, table saw, band saw, whatever saw you have access to)