The Dragon Balls aren't just the namesake of Akira Toriyama's classic series, but incredibly powerful artifacts. When all seven are brought together, a person can wish for almost anything, from eternal youth to the revival of the dead. Throughout Dragon Ball, different versions of these artifacts have been introduced, each time by a Namekian. Earth's original Dragon Balls were created by the Namekian Guardian of Earth, Kami, and were later recreated by the Namekian who replaced him, Dende. Their homeworld of Namek even has its own set of Dragon Balls that are more powerful than Earth's.
But how are the Namekians able to create magical artifacts capable of defying death? The race of green aliens isn't inherently more powerful than other alien races. Frieza's henchmen were able to defeat most of the planet's warriors rather easily. Despite their lack of physical strength compared to Saiyans or other aliens, Namekians are the only race able to create Dragon Balls. Is there a limit to this power and can any Namekian create Dragon Balls?
The Origin of the Dragon Balls
To answer these questions it's necessary to look back at the original set of Dragon Balls that spawned all the rest. The Super Dragon Balls were created by a powerful Dragon God, named Zalama. These Dragon Balls are the size of planets and only grant a single wish when activated. However, this wish has no limits, unlike the wishes of other Dragon Balls, and has been used to restore entire universes that were destroyed. Both in size and power, these Super Dragon Balls dwarf the ones of Earth and Namek.
Far in the past, the Namekians found one of these Super Dragon Balls and chipped pieces off of it to create their own Dragon Balls. These Dragon Balls were much smaller and weaker than the originals but could be used to grant three wishes instead of one. This answers the question of how the Dragon Balls came to exist but to solve the mysteries of their creation, one must look at the powers of the Namekians.
The Namekian race consists of two classes of people: a warrior caste skilled in combat and a support caste, known as the Dragon Clan, that's skilled in magic. The Dragon Clan has multiple magical abilities, including healing and the power to create objects. This is the reason why Kami and Picciolo are able to manifest clothing from thin air -- they are part of the Dragon Clan. This same materialization magic is also how the Dragon Clan Namekians are able to create Dragon Balls.
Because the Namekians were once the only species to have their own Dragon Balls, they were able to hone the magic used to create them so that they could be copied. Each set of Dragon Balls is magically tied to their creator and turns to stone upon their death. Hypothetically, each Dragon Clan member could produce their own individual set of Dragon Balls, like Kami did when he came to Earth. This process takes a long time, however, so it is much easier to modify an existing set of Dragon Balls, like Dende did when he replaced Kami.
Although Piccolo is technically a member of the Dragon Clan, it is unclear if he is able to create his own set of Dragon Balls. After Piccolo fuses with Kami, the Earth Dragon Balls become inert and he's unable to restore them. It seems that Kami's more advanced magical abilities were not transferred to Piccolo when they fused.