If you want one thing that encapsulates the work of particular designer, then in Olle Eksell's case it would be this Eyes Poster.
The Swedish advertising illustrator drew the eyes for Mazetti in 1956 and this logo is the image that remains most closely associated with Eksell. The poster reproduces the logo in pink, green and black on a 50cm by 70cm print. It is sold unframed for SEK 199 (a little under £20).
You can buy the print online at Family Room.