We're using mail boxes as our basic unit. We've looked into custom offering boxes, like you see in parks and all, but as an all volunteer organization with a huge facility to maintain, we've gotten use to being resourceful. The goal of this operation is just to provide a reasonably secure place for folks to make offerings of cash to the Stupas. Sure you could build tank-like boxes out of steel or iron, but these aluminum boxes are sturdy and secure and a lot less work to build. We use our trusty grinder to cut the slots for offerings...