The brain is finite, in size, function and capacity, yet as a universal computer it is capable of any operation given enough time and resources, ultimately everything in the world was created by a brain, albeit one augmented by other brains and other tools, that were also created by brains.
So what factors are important? Memory and imagination are the most crucial aspects of thought. An infinite imagination and no memory would be as impotent as no imagination and infinite memory. What is currently called intelligence, the factor tested with an I.Q. test, amounts to speed of processing, which is rarely relevant. What does it matter if a great idea takes one week vs. ten minutes?
Generally, a small degree of memory is all that is needed, as a pencil and paper, computer, or anything else can augment the memory. There are seemingly no simple augmentation methods for imagination, but this is not so, as inspiration - the root of creativity - can come from anywhere. This is generally a function of networking and so imagination can be increased by increased observation, but also memory of that which is observed. Perhaps imagination, as connector of disparate resources depends then on access to a certain quantity of different types of resources.
We can remember music, drama, images, functions, feelings, locations, events, people (names and faces). We talk of a visual imagination, audio etc. Perhaps the ideal imagination needs a good mix of each type of memory, so that disparate elements can be crossed and fused. Something part Wagner overture and part the image of a dead gnu in the Arabian desert, with a topping of linear algebraic equation. This creates a new mental object. Moving the equation to the middle of this sandwich creates a different mental object.
Imagination is also a factor of youth, as it necessarily demands flexibility. As we age, we become less flexible as our spurious neurons are destroyed, or lined up in new ways. Einstein wore the same clothes each day, thus his clothing imagination had died, unless, of course, he imagined other clothes and merely didn't wear them.
Exercise in this regard then, is crucial. Here are some imagination exercises.
Picture an outdoor scene. Imagine different terrains and locations; woods, hills, a misty mountain in the autumn, the cold arid surface of Mars with gritty red sand, choking yellow gas of boiling Venus air, a black cave with icy breath, a summer day, outside a Medieval castle, underwater.
Change the time, change the location, change the size, change the orientation. Picture yourself as tiny as an ant on the back of an elephant, or as a tiny elephant on the back of an ant. Flip and rotate the image. Change the climate, the colours, the textures. Picture a tree made of glass, or steel, chromium, human flesh. Picture a house inside out, adrift in space, on top of an atom, inside a luscious cream cake.
Explore different senses. Imagine the taste of vanilla ice cream. Imagine the taste with puréed ant, pineapple, blue pineapple. Imagine the taste of yellow vs. the taste of red house bricks. Imagine the smell of the inside of the sun, the warm plastic texture of neutron, or the squidge of a giant cat's tongue, the numbness of ice at the north pole. Imagine how it would feel to be made from concrete, or have six legs like a beetle, or a thin body like a snake. Imagine flying upside down, floating head over feet, or adrift like a dandelion seed over mount Everest. Imagine the room with gravity reversed, or the pressure at the centre of the earth, a solid lump of glowing metal.
Materials to picture; wood (oak, pine, beech, ironwood, balsa, living/dead, smooth/rough, with bark, plain, varnished, stained, painted, tasted smelled), metal (iron, cast iron, rusted, stainless steel, brass, copper, zinc, magnesium, titanium, chromium, gold, silver, nickel, bronze, cobalt, mercury, neodymium, selenium, caesium, soft potassium, indoors/outdoors, solid block/sheet/foil/formed into objects, tasted, cold/warm/hot/molten, glass, crystal, plastic soft/hard, thin/thick, heavy/light, crispy polythene, brittle bakelite...