Recently dismantled a TV and its backlighting consisted of thin cfl tubes. This gave me the material to try something I’ve been curious about for a while!
I sealed some yeast in a little section of tubing for a friend’s birthday (his last name is Baker). Kind of a shitty gift as i doubt it would survive as a keychain but I had fun making it (and its failed predecessors).
Here are the other attempts, from left to right: pepper, red and blue food coloring, yeast 
And here I was running out of ideas of what to encapsulate!
BTW if someone has an idea of something cool to do with this, I’m all ears.
I bought phosphorescent pigment with the plan to make little canisters of ooze from TMNT 2 but not sure what to mix the pigment with…ideally something non flammable, I’ve tried water but it wasn’t super conclusive.
Lube