Here’s a headline on Yahoo! Makers that tells us exactly nothing:
First, consider whether DIY (which is short for “do it yourself”) is synonymous with homemade. It is, isn’t it? So why use both? Then there’s the adjective stationary (which means “not moving”) that lacks a noun to modify. What’s the missing word? Does this headline refer to a homemade stationary bike? Judging from the picture, I think this headline is telling us something: The writer doesn’t know the difference between not moving and writing paper (which is stationery).
If you forget which is which, try this mnemonic: Both stationery and letter contain ER.