I agree, very difficult to model, I've tried before without any real success. However, this time the thought process went something like this:
Fireplace----> Needs a fire---> Ebay, LED candles---> Not really the effect I want, Ok, why not get just the components rather than trying to mangle a 'tea light'---> Ooh,they have flickering orange or yellow or red ---> Hmm, by chance I have discount voucher for this sellers own website ---> Orange & Yellow or Orange & Red? Fires don't actually have much red in them, so yellow and orange should do. ---> LED's arrive, tried wrapping in black weed fabric ( black with holes in), Nah, no good. --->Thinks, what I need is a plastic coal wagon load type thing and drill holes, No that won't work. ---> Could cut a piece of perspex and 'distress' it to get a rough surface so the light reflects at different angles - that might work. ---> At this point, bitter experience came into play and I remembered a couple of failed 3D prints with really random rough surfaces, and from there it didn't take a huge leap to imagine how to force it to deliberately print a rough surface. Then it was only half an hour or so with Sketchup to produce the drawing above, and then another half an hour on the printer.
TBH, I wasn't entirely sure how well it would work, but as they say, The proof of the pudding...
