Braniac75, after trying and failing to replicate the various online recipes for DIY ferrofluid (the consumer stuff is $200+ a liter), figured it out: 1 part iron oxide powder, 1 part "clinging" synthetic motor oil, a stirring stick, and a dangerously powerful magnet to risk your fingers with: "it really is that easy."
The result is more of a paste than a liquid, but it works!
Wanna try ferrofluid yourself but don't want to pay the premium price? In this video I show you how to make your own very easily and cheaply!
I couldn't get the common DIY recipes found online to work well but in desperation found another way through my own experiments. I call it ferripaste since it isn't as fluid as the commercial stuff – but that only makes it even more interesting to play with. It will behave in a more varying ways to a magnet than just spikes like the ferrofluid.
Hope you can use it to make you own amazing ferripaste experiments :)