1.  Spacers & standoffs

• Nylon #4 1/4" spacers: Digikey 
• http://www.ladyada.net/wiki/partfinder/standoff

2.  Screws & nuts

• Machine screws 4-40x3/4": Digikey 
• Hex nut 4-40: Digikey 

3.  Boxes

• Fits an Arduino snugly (102 x 62 x 41 mm): Addison