All vaping and e-cigarette products should be used by knowledgable users and must be at least 18 or older.
Build within the capabilities of your batteries. Always be safe and check your math. https://www.misthub.com/blog/tutorial-ohms-law-vape-safety/
Always remember on hybrid mods (mods which atty center pin touches battery directly) that you need a protruding center pin. If you do not you can vent battery or worse causing serious harm.
Here is a link to some excellent references for new and seasoned vapors alike. courtesy of VaporBeast.com http://www.vaporbeast.com/new-to-vaping/vaping-guide.html