Infill Patterns: The parts you never see as a client.
When making something, it is very rare that it ever needs to be completely solid. That is usually a waste of material when the actual strength of an item lines along 'lines' where the stress actually is. Think skyscrapers and 'I' beams. Even the b building itself is not solid, only the outer edges are really.
To that end, here are a couple of infill patterns that are used(there are many in reality).
This is an image of one of the failed attempts when I was printing that Low-Poly Bear. You can see it's basically 'square', although rotated in a kind of diamond pattern. This is what 15% Infill looks like. Meaning, 15% of the space is used up with filament to create the inner structure. Obviously 100% would be solid. This is a very strong structure and does the job very well.
This is a very funky pattern of wavy lines. As it grows in height, it will actually 'rotate'. This gives it a very strong structural integrity. It's also just really cool to look at and watch while it prints.
Why would one use either pattern? For a number of reasons really but in the case of the Nintendo Switch Lite wall mount here, I needed something that gave more of a surface when laying down a completely horizontal surface(top) because the strands needed more support to lay on and this fit the bill, while only using 3grams more of filament, although it does take an extra 3hrs because there is more movement in the print head vs the straight line of the adaptive cubic infill pattern.