The versatile chemical engineer and inventor Slavoljub Eduard Penkala was born in Slovakia. In scientific circles, he is best-known for inventing the mechanical pencil (the pen), called the penkala. Upon moving to Zagreb in 1900, he took on the Croatised name “Slavoljub”.

Penkala’s first inventions were the termofor (a forerunner of the Thermos flask) and a toothbrush with a rotating head. Throughout his life, Penkala held around 80 patents for inventions such as the fountain pen and pencil holder (the so-called knipsa), the anode battery, a rheumatism medicine, the Krepax powder (insecticide), a powdered laundry detergent, a bluing detergent, the dynamometer, the stylus etc. His crown invention was the Neptis lucilla, the first aircraft in Croatia, built between 1909 and 1910.

With the Moster brothers, he founded the Penkala-Edmund Moster d. d. factory in Zagreb, which manufactured penkalas and other stationery, such as ink, India ink, glue and fountain pens, as well as the first phonograph records. From 1912 to 1926, the factory was one of the biggest manufacturers of writing implements in the world, exporting to more than 70 countries and employing around 800 people.