Product designer Konstantin Achkov has created a range of flat-pack furniture that slots together like a puzzle. Called Stack, the pieces are assembled without glue, screws or other fixings. The collection so far includes a round table, bar stool, chair and armchair. Each one is made of 18mm-thick beech plywood, cut with a computer-controlled router. The pieces were presented at Sofia Design Week from 1 to 8 June. A graduate of Sofia University, Achkov plans to launch his own brand calledTenon to produce this range and his previous work.