Hi! I haven't been on the server for awhile (holidays).
When I first started, I checked with my insurance carrier first. Got it approved. Then I continued perfecting the sanding & cutting to make sure there wasn't any cracks or anything else with the edges (there are a lot of companies who don't do a fine inside or outside bevel edge). I also did the heat/temperature differential tests that the Candle Association recommends (thus documenting all of my findings incase there was a future problem). I have only had one candle crack on me (and it was mine), but this was from power burning the candle for about 8-10 hours, and I saw it had a chip at the top. The candle didn't explod, it just had a hairline fracture down from the chip.
So, yes there are a bunch of concerns, yet most of these are mainly general candle making tips. I suggest checking with your insurer, and cover your ass on the warning label. LOL.
These type of candle take A LOT of labor..... I am a perfectionist, and thus this leads to way more labor than I actually wanted to spend on a single candle (but I want my quality to be better than what is locally available). I'd suggest asking yourself first on how labor intensive you want the container itself to be. And then determine if your willing to take the risk. Good luck.
oh----double check your wicking for when at the bottom of the vessel. Be sure that the tab doesn't slide of the punt. If it does, that will create a dangerous situation.