These wooden storage boxes by Japanese designers Torafu Architects stack up to make little trolleys (+ slideshow).

Koloro Wagon storage units by Torafu Architects comprise three colour-coded trays with pivoting handles that allow them to be separated and carried like shopping baskets.

The L-shaped uprights of the handles will brace against the bottom of the box to stack the units vertically, with the cross-bars fitting into grooves on the underside of the box above.

The bottom grooves will also accommodate the axels of a pairs of wooden wheels to form a trolley.

"In today’s world, one space may be used alternatively as a dining area, work area, and child’s play area," said the designers. "What we propose here is a moveable storage cabinet to suit changing lifestyles, in terms of functionality and individual needs."

The trays come in sky blue, white, yellow, dark green, pink and grey.

"Given the variety of colours available, the boxes can be designated by colour according to the needs of the family," said the designers. "One for a child's toys, one for a mother's hobby materials, one for a father's business documents and so forth, or according to their purpose."

Torafu Architects created the system for manufacturers Ichiro, who also manufacture their Koloro-desk that looks like a dolls' house.