Wooden chair
According my teacher the chair without arms is one of the most challenging object of furniture to design as you need to consider so many functional aspects together with aesthetics. At the same time it must be ergonomic, durable, feasible, movable(light), even stackable and all these should be packed in visually balanced construction. As in the chair with arms, chair without arms don´t have luxury of this element to give durability and some cases comfort or ergonomics, but you must find way to reinforce as such light structure. Here is one study and solution to this dilemma. Combination of solid wood together with plywood enables structure that is durable, elegant and has strong sense of material. Seemingly simply and classic wood chair hold the interest in structural details that are exposed on sides. In this case I did not consider stacking as I wanted to keep solid lines and classic uncompromised look, this could be another study.
Tangent break in middle of the seat increase durability and enables ergonomic comfort.
Wooden frame wrapped with plywood locks most critical spot of structure and structural detail of the frame stays exposed. 
Front legs are mounted to the wooden frame through the perforation.
Alternatively front legs could be metal and plywood structure continues until floor behind.