This video, from youtuber MrGear, shows you how to hollow out the bottom of a candle and make a secret compartment. Use a power drill with a hole cutting bit and drill into the bottom of a large, decorative candle (pull off the sticker and hold onto it for later). Then carefully carve out the rest of the hole with a knife.
You could also use a wood spade or paddle bit if you want to do it all in one go. Keep all of the wax you drill and cut out, reshape it into a disk by melting it all in a jar lid, and shape the disk so it fits into the hole at the bottom of the hollowed out candle. Now stick your cash or valuables inside the candle, place the lid over the whole, and melt it shut with a lighter or mini-torch.
Once you put the sticker back on, the candle looks good as new. No one will ever suspect there’s anything inside. Of course, once the stuff is in there, it’s not going to come out very easily. This trick is probably best for hiding some emergency cash or something you don’t need to get to regularly.
How to Make a Secret Candle Compartment [YouTube]