To buy and resell (a house, for example) in a short period of time for a profit.
It's commonly, but not exclusively, used when talking about people buying and re-selling houses. You could certainly say, "She's been making money flipping smartphones on eBay."
The technical term for these structures seems to be either house or bulkhead (e.g. stair/elevator house or stair/elevator bulkhead), but satisfactory online definitions are hard to find.
bulkhead
a boxlike structure built over an opening, as at the head of a staircase, elevator shaft, etc.
Elevator house or bulkhead Structures with elevators may have an equipment or motor room located on the roof. Elevator houses vary in size according to the number of elevators that they service...
Best Answer
According to howstuffworks.com, How Ballpoint Pens Work, it is called an ink resevoir:
However, in a context where you need to buy more and you're at the store, I think that you should ask for pen refills. From Office Depot: