[Source: http://www.thisiscolossal.com/2011/05/the-inception-chair/, Artist: Vivian Chiu]
These are series of ten interlocking chairs made of ash. Each chair has hand cut grooves on the inside edges of its seat frame as well as notches in the seat back. These grooves range from 1/2” wide to 1/8” wide. The mechanism works so that the pegs fit into the grooves of the chair one size bigger and slides into place so that the horizontal edge between the chair seat and back line up. The simple mechanism allows the chairs to be taken apart and put together with ease.
In other words you need all ten chairs to be interlocking with one another before you can take a seat.
reported by Alexander Tan Sze Hui