With mine I used the black foam board from the dollar store, because at other stores this stuff is about $4 a board. Since it was cheap, the edges of the black board were white and didn't look quite right so I glued ribbon where the white was showing. I also took thin wooden rods (from Hobby Lobby or Walmart) that were about $0.25 a piece, cut them to the right size, painted them to match the ribbon, and then hot glued them to the sides so that my nail polish won't fall out.
Here's my finished product:
