Another Japanese design studio with a great idea! D-Bros ”Booooon” (an onomatopoeia often used by children to imitate the sound of vehicles – it must be a Japanese thing!) envelopes make the excitement of receiving a real hand written letter, an event in itself these days, even more thrilling. Each envelope comes with an illustration of an automobile, locomotive and airplane and when torn open they create trails of exhaust plumes! An inventive idea for even the biggest of kids but sadly only available in Japan at the moment.