Build Your Own Lava Lamp
No, really, it is possible!
At least, according to this website, it is. Now, I haven’t actually tried this myself, so it could be harder than it looks. And, anyone under 18 should get approval and help from an adult. But, they do have several “recipes” for making lava lamps, including a link to one that has a “Kids Version“. (But, the approval thing sill applies!)
Anyway, it looked like a fun one for a Friday!