ㄴ 거 만들다

make a big or cheap one

-ㄴ 거 turns a description into 'a ~ one', so you can name what you are making by its quality rather than by the thing itself: something tasty, a big one, a long one, a cheap one, a weird one. It is the everyday way to talk about making things when the noun is obvious or does not matter. 만들어 먹다, in the first line, is specifically making your own food and eating it.

Register: casual