Wirkkala began his career as a sculptor and through his works in plywood he acquired a unique position in between applied art and sculpture. He was one of the earliest representatives of abstract sculpture in Finland.

Wirkkala's best-known plywood sculpture was most probably Ultima Thule, which he made for Expo 67 in Montreal.

Tapio Wirkkala did not wish to mark any boundaries between his work in sculpture and design. For him, they were about  the same thing.