Depending on the type of shell you wish to make, you will need more or less equipment.
For a simple shell that has no embeds in its sides, a regular container or mold (a large Tupperware, for example) is all you will need.
On the other hand, if you want to include various decorative items in the walls of the shell, you will need an insert to keep the embeds in place while the paraffin sets.
The tricky part will be to find an insert that has the same shape as the mold but in a smaller size...
As I mentioned in the introduction, the choice of mold available to you will depend on whether you want to include embeds into the walls of your Hurricane shell.
Let's have a look at those two cases separately:
In this case, any container large enough will do the trick. I say "large enough" because the flame of the votive or tealight candle that will burn inside the shell must be far enough from the shell walls or these walls could potentially melt.
Basically, all you have to do is is fill the container (or mold) with paraffin wax, wait for it to start setting and walls to form then remove the skin at the surface and pour the still liquid paraffin back into your melting pot. Once you have smoothed the inside of the shell walls and the shell has cooled off completely, you can remove it from the mold, level the edges with a knife and either paint it, glue decorative elements on the outside or just leave it as it is.
This is pretty much all you need to make a Hurricane shell without embeds. That wasn't too painful, was it?
This is a whole different story. Most of the time, the decorative elements you try to include will have the annoying tendency to float and, if you don't manage to keep them in place one way or another, you will find them all joyfully floating at the surface of the wax, which is not exactly what we want them to do.
To keep artificial flowers and other decorative elements in place, there's no better way than using an insert (also called sleeve), a hollow piece of equipment the same shape as your mold and at least as high (preferably higher) but with a diameter (or section if your mold is not a cylinder) about 2 cm smaller than the mold (depending on how big the embeds you want to use are).
The idea is to place the insert inside the mold and wedge the embeds between mold and insert. Doing this should keep everything in place while you pour the paraffin and while the paraffin sets.
The hard part, as mentioned above, is to find an insert that has the general same shape as your mold (it will prove almost impossible to wedge anything between a square mold and a cylindrical insert or the other way around) but is slightly smaller, just enough to keep the decorative elements safely in place. More about this further down.
The general modus operandi is as follows : insert your embeds between the mold and the insert (using one or two knitting needles makes this step a lot easier), pour the melted paraffin wax at the center of the insert (not between mold and insert or you will displace the embeds every time), place the mold in a cold water bath (see below) and, working at a speed of about 2 centimeters per minute, remove the insert. When done, proceed as you would with a shell without embeds (leveling and trimming).
Both methods are explained in great detail in the article Hurricane candles - How to make them ?
As usual, you can choose between commercial molds and household items that you will turn into temporary hurricane molds.
The one big advantage is that, when you buy a mold that is specifically made to create Hurricane shells, you normally have a choice of optional matching inserts (there should always be at least two sizes available).
Nevertheless, there is always a way to create an insert that will fit a commercial mold (see below).
Most Hurricane molds are made of metal but, although not really recommended, you will also probably find polycarbonate Hurricane molds.
Both have pros and cons : metal molds last pretty much forever and have a base that makes it easy to attach a weight before you dip the mold into the cold water bath. On the down side, putting the decorative elements into place is a bit of a pain as you don't see precisely where they end up.
Polycarbonate molds are see-through and allow for a precise positioning of the embeds but they are also usually "baseless" and are tricky to weigh down and manipulate when the time has come for their bath. Also, they are not as long-lived as metal molds, obviously. The choice is yours; I prefer the metal molds for their sturdiness and because they're easy to lift and move.
With a little bit of imagination, there is a whole world of items that can be turned into Hurricane molds. Only two things can potentially disqualify an item : its size (we've talked about that) and, of course, its ability to withstand the heat of melted paraffin. Other than that, it's up to you : biscuit tin, large tin can, a vase of appropriate shape and proportions, soup bowl, fruit bowl, large Tupperware, 1 gallon water bottle, football cut in half.... and many, many more.
Let's talk about inserts : if you ever buy a commercial Hurricane insert, you will notice that the cylindrical ones look alarmingly like aluminium stovepipes. It's probably because... they are. So before you pay good money for commercial Hurricane inserts, have a look in the aisles of your favorite DIY store : stovepipes are available in different diameters and lengths; all you need now is finding someone with a grinder who will cut the pipe to the right length and deburr it.
If you need another shape than a cylinder, you can always purchase a small aluminium plate, have it cut to the right dimensions and fold it into the desired shape.
Dipping your Hurricane mold into a cold water bath will let the paraffin cool off and set much faster. This presents several advantages, and not only where Hurricane candles are concerned.
But in this case, the intention is to quickly freeze into place the embeds that have only one thing in mind : to float at the surface of the wax. If you embed artificial flowers, the cold water bath will also prevent (or at least greatly reduce) color bleeding.
The cold water bath is an important enough technique and therefore has its own article that you will find here.
Do not underestimate the amount of paraffin you will need to make a Hurricane shell !
Most of the time, your mold will have to be filled to the brim and a Hurricane mold is not exactly small.
One good way to know what quantity of paraffin you will need is as follows : fill your mold to the brim with water, then pour the water back into a measuring cup.
Back to school. Assume we have a cylindrical Hurricane mold 20 cm high and with a diameter of 16 cm : volume of a cylinder = (radius x radius) x 3.14 x height; in this case, (8 x 8) x 3.14 x 20 = 4019 cubic centimeters so a bit more than 4 liters (or 40 x 10 centiliters) -> according to the formula above, you would need for this mold 40 x 116 grams = 4.64 kilos of paraffin ! Hard to believe, no?
It's a good idea to write down this information for each one of your molds in your notebook, so you won't have to repeat it every time you make a shell because you forgot the exact figure.
To hold such an amount of paraffin, you will need a melting pot significantly larger than what you would normally use. As illustrated above, I use my regular double boiler container (which is already large enough) together with a saucepan that holds just over 5 liters. It's only just enough to hold the amount of wax necessary to fill my largest Hurricane mold.
When you pick a saucepan, be aware that there has to be at least 1 centimeter of free space between the outer and the inner one. Which means that the inner one must be at least 2 centimeters smaller.
In other words, when one saucepan is placed inside the other one, you must have at least a space of 1 centimeter in between; if you don't, the boiling water will not have sufficient room to boil freely and hot water will burst out of the combo, even on a very low heat.
This little accessory is not needed to create a Hurricane shell but it has its place here because it is essential to use a Hurricane shell.
Although some candlemakers like to make bottomless Hurricane shells (in other words, an open cylinder - its is indeed easier, if the shell is high, to fit a votive or a tealight candle inside), most of the time the shells you create will have a wax bottom.
And to protect the bottom from the heat generated by the core candle (especially so when the flame of the latter reaches the bottom of the votive holder or the tealight cup), it is necessary to place a coaster under the core candle.
This coaster must of course be made in a material that is non flammable and heat resistant (otherwise, there's no point using one).
The best I found so far are small cork-covered coasters, like the one you see on the picture above. They cost next to nothing (shops like Dollar Store usually sell them) and do a very good job at protecting your shells.
The day you find a votive holder irremediably welded to the bottom of your Hurricane shell, as it once happened to me, you will understand the value a simple little coaster adds !