Bunk Bed

Source corner braces from Menards http://www.menards.com/main/tools-hardware/household-hardware/utility-hardware/corner-braces/3-1-2-corner-brace/p-2155800-c-9700.htm

this is another alternative http://www.mymobilecommunications.com/index.php?route=product/product&product_id=67

or we can make them ourselves from plates as shown in the animation... but this design needs countersunk holes to sit flat so maybe it isn't appropriate.