FIRST4MAGNETS EFH1 Ferrofluid 20ml for Science, Education, Experiments, Students, and Teachers - 500ml Bottle

First of all, nobody is kidding about the mess. Don't think "oh, I'll just be careful" because this stuff has a mind of its own and I spilled it just opening the lid to pour it. But there is a warning in the leaflet, and so I was well equipped with gloves, foil tray, jar with a lid, newspaper and kitchen towels etc.And it is a lot of fun to play with! You'll need pretty strong magnets, though - school-grade buy-in-bulk red and blue iron magnets didn't do the cool spiky thing you see in photos and videos. Buy neodymium magnets if you want to see the spikes.

Worked really well but had to decant into safer bottles as the bottles they came in leaked

pretty cool. the more you put in the more it reacts. 8 yr old found it 'aweome'! as did we! Be very careful though. We put it in a clear container and wrapped sellotape around and around the seal to ensure none escaped. don't get it on your skin. I bit splashed on me and it burned a touch, but cold water soon sorted it out. No marks left on my hand.

messy beyond belief with the oil base staining skin badly.... read the instructions first (at least twice) then give it to a science teacher

Very cool desk toy. We are now trying to put it in a bottle and not make it stain the sides of the glass. Other than that, it is a very interesting and inspiring toy to play with.

Doesn't work like it says it should no intrusions how to do it

This was just the most fun I've had as an adult for a long time. We may have destroyed a couple of magnets but it was worth it