The phrase "eccentric inventor" refers to someone who is very creative and imaginative but also a little strange or peculiar in their behavior or ideas. It describes someone who comes up with unique and unconventional inventions. Full definition
One of his largest film roles was as the delightfully eccentric inventor Alva P. Hartley in the 1944 Laurel and Hardy vehicle The Big Noise. (rottentomatoes.com)
An eccentric inventor and a murky group of retired military brass — most of them with plenty of medals but no experience in commercial nuclear energy — have peddled various incarnations of the plan for years. (businessinsider.com)
But you will never see Dean Kamen in a suit and tie: the eccentric inventor dresses almost exclusively in denim. (scientificamerican.com)