What home chemical can I use to make droplet lens?

I'm very interested in making homemade droplet lens, I want to know what home element can I use to cook them. 


Here's a video showing the process, with no further information:


<https://www.youtube.com/watch?v=NQLWS5j8gB4>


And a research paper about it:


<http://www.opticsinfobase.org/boe/fulltext.cfm?uri=boe-5-5-1626&id=284161>


