Applied Magnets Magnetic Ferrofluid -2oz- 60ML Bottle, Great for Science Projects

I put half the bottle into a used glass jar for good visibility. It works really well with my collection of neodymium magnets. Nice clearly defined peaks and spikes. It is very dark fluid and staining, to the point that I don't want to bring the glass jar anywhere because sloshing of the ferrofluid will darken the walls of the jar at least for a good long while. For demos the best bet is to bring a clean clear glass jar, and pour the ferrofluid carefully after you arrive to a place where you can ensure minimum sloshing, for best visibility.

本来の使い方とは違いますが、木や骨や自然の素材でアンティーク作品を作るときに、これを塗ると大変味がある良い仕上がりになりますので重宝しています

First of all, this stuff is amazing, and you get plenty of it. Nothing that follows is a complaint, just a few warnings. This stuff is really messy. It's essentially motor oil, so cleaning it off your skin isn't pleasant, but cleaning it off of magnets is even harder. If you have it near magnets, it will find a way to get to them - the fluid will essentially aerosolize and re-form around the matnet, which is really cool to watch and really annoying to clean up. I suggest keeping it in a glass bottle, as small and thin as possible. The stuff will smear across the sides, so if you play with it too much you won't be able to see what's happening, but it's still neat.

I put in in a fishbowl of water and taped magnets to it. Fun times.

This stuff is pretty fun when you have some powerful magnets. It's a little expensive though. It stains anything and everything like crazy. You should buy some sort of pipette or dropper to transfer it from the bottle to a container. I highly recommend using latex or those types of gloves while handling it since it stains skin easily. Be careful too, it will leap out of the container around high power magnets. (Almost impossible to get off the magnet then) There are a lot of youtube videos of cool things you can do with this stuff. If you are just checking it out casually, I suggest getting a smaller amount first.