David Unaipon
Unaipon took out provisional patents for 19 inventions, but he could not afford to get any of his inventions fully patented. His most successful invention was a shearing machine (provisional patent 15 624) that converted curvilineal motions into the straight-line movement that is the basis of modern mechanical shears. Unaipon never received any money from it, however. Apart from a newspaper report in 1910 acknowledging him as the inventor, he received no credit.