Which reminds me Four Winds, another possible about Bullauns, to add to the thread a while ago.…Not to burn candles, but as candle moulds?
Looking at all your pictures, yet again, I'm struck by the fact that the ones with rainwater in always seem to have the water in a very nice round shape, even though the upper part of the bullaun may be less round and less on the level.
It's hard to tell from the pics if bullauns are flat bottomed. Not that that would prove anything as the way to make container candles is upside down, so the flat top becomes the perfectly level base.
As a one-time candle maker (!) a couple of other things ring a bell with me. First, being near water would be good as you'd need to cool them down rapidly at a certain stage in order to ensure they could be pulled out easily. Some seem to have a reservoir so you could pour water above the candle and leave it there. Second, some seem to have possible overflow channels, and there's even two shown with an interlinking channel. This is SO typically candlemakerish, as it's common practice as it allows you to easily make exactly standard sizes! (Points to a commercial mindset, not a shamanic one!)
I suppose the theory could be made or broken by seeing if "down" was at right angles to the top of the liquid. If not, the resultant freestanding candle would be wonky. A cast of the interior is what's really needed.
Can't find any reference to Neolithic candles, except suggested container candles. The thing about those though is that they'd be hopeless as they burned down because the containers wouldn't be glass, so freestanding ones would be much more likely. I love the idea of a village communal candlemaking facility, next to the village water supply and village washing stone.
Please don't say this is wrong as I want to acquire a bullaun and restart the business selling genuine Neolithic candles…