One day, the trickster god, Loki, was feeling especially mischievous and decided to cut the golden hair of Thor’s wife, Sif. Thor was angered by this and hunted down Loki and told him that if he did not reattach the hair to her head by the end of the day, he would rip his arms and legs off. Cowed by this, Loki had an idea. He went to the home of the dwarves and found the best blacksmiths in the land. He then had the sons of Ivaldi forge him three gifts for the gods. Not only did they forge a head of golden hair for her, but they also made a ship that could fold up to fit into a pocket and a spear that always struck true. Even still, Loki was not satisfied and wanted to trick more people.
He went to two brothers who were blacksmiths named Borkor and Srindri. Not convinced of Loki’s lies, the brothers demanded something in return. They wanted Loki’s head as a reward for completing their task, and begrudgingly, Loki agreed to this deal and the brothers set to work. First, putting a gold bar and a boar’s head in the forge, one brother said that the bellows could not stop pumping or the final product would be ruined.
Hearing this, Loki had a plan: he transformed into a horse fly and began to viciously bite the hand of the brother pumping the bellows, but throughout the pain, the brothers persisted and out came a boar that was faster than the wind and could be ridden.
Placing another block of gold in the forge, the brothers began again, and Loki struck again, biting the scalp on the brother who was pumping the bellows. While he erupted in profanities, he continued to work, and out came the second gift: a gold ring that split into eight identical rings every eight days.
Next, the brother stressed the importance of this third and final gift. It would be a masterpiece and could be ruined if he stopped pumping the bellows for even a second. The brothers set to work, and Loki, now needing to ruin the gifts in order to keep his head, bit the eye of the brother repeatedly. Overcome by pain, the brother took his hand off the bellows for a second to swat at Loki, and the bellows stopped moving. So when the gift was done, it had an imperfect handle (it was too short), but still they were done. The hammer Mjollnir was complete.
Taking the gifts, Loki hurried to the hall of the gods to present the gifts. He placed the golden hair on Sif’s head– it was even more beautiful than before– and he gave the other gifts to the gods as well. Thor received the famous Mjollnir, but then the dwarves arrived and told the gods of their bet with Loki, they all agreed that Loki owed them his head. Loki argued that they did have the right to his head, but they did not have the right to cut his neck, and to the dwarves’ dismay, the gods also agreed. Angry and cheated, the dwarves went home and Loki lived to see another day.