Stockholm 2012: these outdoor chairs by Stockholm designer Thomas Bernstrand are joined together like shopping trolleys to encourage park visitors to tidy them away when they leave.

Having visited parks in Paris where chairs are available for people to place where they want, Bernstrand liked the idea of not being confined to fixed benches but felt sorry for the person who has to collect the chairs in order to cut the grass.

The Share system requires users to insert a coin to release a chair from the chain. The coin is released when they return the chair.

Bernstrand presents the prototype with outdoor furniture brand Nola at Stockholm Furniture Fair this week, which continues until 11 February. See all our stories about the event here.

His previous projects include stackable slanting shelves for Swedese and furniture for an artificial beach.

"I like to design furniture for the outdoors because I can go there and see how people are using it," says Bernstrand. "Once I went back to one of my benches and it was half burnt."

Here are some more details from Nola:

SharePortable Park Chair Designed by Thomas Bernstrand

Share chairs are lightweight outdoor seats designed to nest within each other as they attach to an immovable base. Like the attachable trolleys used in super- markets and airports, the chairs are equipped with coin-operated locking mechanisms that link them together when not in use. Made for parks, city squares and shopping centres, the chairs are mobile seats that individuals can place where they want to. Share chairs provide more flexibility than fixed seating, as they can be positioned to face the sun, enjoy the shade, or take advantage of the view.

The chair’s locking mechanism can be operated by a coin or a token, encouraging users to return the chairs to the correct location after use. Designed similarly to stackable chairs, Share nests inside each another, making them easy to store when returned to base.