To begin this project, you will need a few materials and tools.

Latex-free Disposable Gloves
X-Acto Knives
Corrugated Plastic Sheets
Plastic Cups with measurements
Plastic Stirring Utensils
2 Part Epoxy Resin
Resin Coloring (Optional)
Model of a Large Crystal
- Foam Core Board (If you will make your own crystal model)
- 3D Printer (If you want to print my 3D models provided)
Double-sided Foam Tape
Hot Glue Gun
2 Part Silicone for Mold Making
Scrapped USB cord (For taking apart and rewiring)
1-3 small LEDs
Electrical Tape or Heat Shrink Wire Insulators.
Wire Strippers
Soldering Iron (Optional)
Dremel or Drill
Heat Gun or Hairdryer

Step 1: First Step: Crystal Model

You will need a crystal to make a mold out of! For this, you can use a large crystal you already have, or you can make your own.

The first way you can make your own is to cut out a net on Foam Core Board. I have provided some net templates that you can print out largely on a sheet of paper then use an X-Acto Knife to cut out on foam core board. On solid black lines, cut all the way through, and on gray lines, cut half way through. Do this all on one side, then fold up the net to form a crystal, and use hot glue to seal the edges and close any gaps.

The second way you can make a crystal is to 3D print one! I have some models to provide, free of charge, of crystals. With these, you can skip step. They are in the attached files and there are preview pictures, click on "2 More Images".

Other ideas of how to make your crystal:

Model one out of clay, using a knife or wire to get flat edges and a spoon, knife or sculpting tool to carve a semi-oval out of the bottom. I highly recommend coating it with a few layers of Mod Podge or some type of sealant.
Carve an old candle to get a wax crystal
Be creative but make sure whatever you make will be sturdy enough to be pulled on and wiggled out of the silicone mold!
Make sure that if you are making your own crystal, leave a hole in the bottom like you see in the 3D models. This will make the light shine through the crystal better.

Step 2: Second Step: Mold Holder

The tools you will need for this step:

Corrugated Sheet Plastic
Pen and Ruler
X-Acto Knife
Hot Glue Gun

The second step is to make your mold holder. Measure the dimensions of your crystal when it is laying on its side. You want to measure the length(A), width(B), and height(C). Use those measurements to cut 2 pieces of your corrugated plastic sheet. One piece will be long. To find out the length of the rectangle you need to cut, add your length with 2 additional centimeters and width with 2 additional centimeters, and multiply by two. Here's a simple equation. ((A+2) x 2) + ((B+2) x 2) = the length of your rectangle. To find out the width of the rectangle you need to cut, you simply use the height of your crystal and add 2 centimeters. Go head and use a ruler and a pen to trace out this Long strip, making sure the longest sides are perpendicular to the lines in the corrugated sheet plastic. Also mark the folding lines on the sheet plastic. Then cut the perimeter out all of the way through with an X-Acto knife as cleanly as possible, and then on the folding lines, cut half-way through the corrugated sheet plastic.

To get the Base, use the length and the width of the crystal model, and add 4 centimeters to each measurement. Use a ruler and pen to trace out the Base, then cut it out with the X-Acto Knife.

Fold the Long strip into a rectangle along the folding lines, meeting the two ends and then use a hot glue gun to connect them evenly. Then center this on the Base, and firmly glue it down, making sure not to leave any gaps, or the mold putty will later flow out. Check your box for any gaps and fill them in. To double check, fill your box with water and look for any leaks.

Step 3: Third Step: Making Your Mold

A helpful, in-depth Instructable that you may find helpful is Paige Russel's Mold Making & Casting Class .

For this step, you will need:

Latex-free Disposable Gloves
X-Acto Knives
Your Mold Holder
Plastic Cups with measurements
Plastic Stirring Utensils
Your Model of a Large Crystal
Double-sided Foam Tape
2 Part Silicone for Mold Making

This is the step with the most supplies. It is also one of the messy ones. Make sure to cover your work surface with layers of paper, newspaper, wax paper, or whatever is accessible to you that will also do a good job of protecting your surface. Be sure to wear your Latex-free Disposable Gloves throughout this whole step. Trust me, it is very annoying to have sticky hands or to have to walk over to the sink and scrub your hands while you have a time limit on the silicone setting.

The first step to filling your mold is placing the object you are making a mold of securely into your mold holder. Use a 2-5 cm strip of Double-sided Foam Tape to fasten your crystal to the bottom of the mold holder. You want to use a flat side of your crystal and place the Double-sided Foam Tape in the middle of that face. Then center it in your mold holder and press down firmly to secure it.

What I recommend for finding the amount of silicone you will need is fill your mold holder with the crystal in it with water or rice, something that fills the volume easily, and you want to fill it up 2 centimeters past the top of your object. Then pour it out into a container with measurements or separate plastic cups with measurements, and add up or find the volume. This is how much silicone you will need for this project. I recommend adding a bit extra to that total, because it is always better to have too much than not enough.

Mix up the amount of silicone that you need in a clean container or plastic cup and stir with a clean stirring utensil that you know you can throw away, following the directions of the brand of silicone you got. Some brands have different ratios of how much to mix together and different setting times. Slowly pour it into a corner of your mold holder. Never pour the silicone directly onto the object you are casting, because it can lead to air bubbles under the edges of your object. Pour from 15-25 centimeters above and move to a safe place to set for at least 24 hours, or however much time is recommended on the packaging.

While your mold is setting, go on to step four and return when your mold is set.

When it is time to remove your silicone mold, you do not want to cut into the silicone until you have fully taken it out of the mold holder. You want to pry the sides of the mold holder away from the block of silicone, and feel free to cut the corners of your box with the X-Acto knife to make it easier to peel the pieces of the mold holder away from your silicone.

Once you have your silicone mold out of your mold holder and flip it over, so the side with the little rectangle of tape is facing you. Remove that rectangle of tape with your X-Acto knife for assistance. I recommend to carefully use your X-Acto knife to cut half way through the height of the mold to make removing easier, and cut out the thin layer of silicone on the side with the tape tracing the line of the edge of the face of the crystal.

Your silicone mold is now ready!

Step 4: Fourth Step: Making the Base

To be able to put your crystal on display, you need a nice thing to display it on. While your mold is setting, look around for a base with a flat bottom and a flat section on the top that can easily fit the bottom of your crystal on top. I simply used a small square piece of wood, but feel fee to get creative and use other small shapes of wood, make one out of resin, 3D print one, sculpt one, or many more options. Just make sure it is about an inch thick.

For this step you will need:

Despite whatever material you choose to use, you need to find the center of your base, or the center of where the crystal will sit flat on its bottom face. Use a ruler for accuracy, and a pencil, so you can erase your marks later. Now where the center is, you want to prepare to drill through it using your Drill or Dremel, making a hole that is about a centimeter in diameter. you will soon thread your light through this.

On the opposite side of the side you want to face up, aka. the bottom of your base, you want to use your Drill or Dremel to make a channel from an edge to the center hole. This channel should be as straight as you can get it (even if it is a little wiggly, you will be fine), and shallow, but deep and wide enough to hide small wires through it.

After you have made the hole and the channel, go ahead and decorate it any way you want, as long as you do not fill the hole or the channel. I simply painted mine black.

Step 5: Fifth Step: Making Your Resin Crystal

Now that you have your silicone mold done, you are ready to cast your resin crystal!

For this step you will need:

Your silicone mold
2 part Epoxy Resin
Latex-free Disposable Gloves
Plastic Cups with measurements
Plastic Stirring Utensils
Resin Coloring (Optional)

If this is your first time working with resin, do some simple tests, pouring about 30 mL of resin that you made into clean cups. You want a non-sticky, not too bubble filled result. For a casting this, you will most likely end up with bubbles in your resin, because it is on the bigger side.

*If you had to cut half way through your silicone mold, simply put tape over the cuts to just hold them in place. I used scotch tape and it helped prevent any problems.

To find out how much resin you want to use, fill the crystal mold with water or rice, something that fills the volume easily. Then pour it out into plastic cups with measurements, and record the volume. Add 10 mL extra to the total, because again, it is better to have too much than not enough. Follow the instructions that come with your resin, because every Epoxy resin could be very different, like the ratio of different parts and the setting time. Add any coloring you wish if you have it, but use a very small amount so light can still shine through. Make sure to wear you Latex-free Disposable Gloves throughout this whole step! Resin is even worse than silicone to get off your hands!

As that sets, go ahead and and work on the next step.

When it sets, go ahead and take it out.

If you do not use a crystal with a hollow center, you need to make one in your crystal once it is set. Use a dremel with a sanding bit to carve a semi-circular hole in the bottom face that is about 5 cm deep and leaves 1 centimeter between the edges of the bottom face. Try to make it as smooth as possible so light can easily get through it.

Tips:

Make sure to pour the two parts into separate cups, then pour them in the same cup after measuring each out.
Mix well, but not quickly. Make sure not to whip it at all to avoid getting extra air bubbles in it.
Pour slowly and from 10-25 cm above to reduce the amount of air bubbles.

Step 6: Sixth Step: Wiring

What you will need for this step:

1-3 small LEDs (I used color changing ones because my crystal was colorless, but you can use white or any color you want)
Electrical Tape or Heat Shrink Wire Insulators
Wire Strippers
Soldering Iron (Optional - you can twist the wires together after stripping them)
Scrapped USB cord (For taking apart and rewiring)
Heat Gun or Hairdryer
Base

So you want to first find your positive and negative wires. You can figure that out by simply plugging in your USB cord and touching each leg of one of your LED's to different wires. The longer leg of LED's is the positive side, and the shorter leg is the negative side. Once you find them, separate them and label them. Unplug your cord while you work with it. Use your wire strippers to strip off about a centimeter of casing from the wires. Heat up your soldering iron if you want to solder your wires to your LED's.

*If you are going to use Heat Shrink Wire Insulators, place them on each wire before soldering your LED in place. If you are going to use electrical tape, wrap each soldered area separately.

If you have one LED, simply wrap your stripped wire ends around the corresponding legs of your LED, and if you wish, you can solder them in to place. After you solder them, use your Heat Gun or Hairdryer to shrink the Heat Shrink Wire Insulators. If you will not solder them, wrap them with electrical tape right after

If you have multiple LED's, make sure the positive legs of the LED's are grouped together, and the negative legs are grouped together. Now follow the steps in the paragraph above.

Step 7: Seventh and Final Step: Putting Everything Together!!

For this step you will need:

Hot Glue gun
Finished Crystal
Finished Base
Finished Wire

Once your wiring is done, it is time to put your creation together. Start heating up your glue gun. Get your Finished Base and hold it in one hand and your finished wire in the other. Poke your LED's through the hole that you made in your base so they come out a centimeter or two from the top face of your base. You want to keep them there. Bend your wire where it is sticking out at the bottom and lead it from the hole, through the channel you made, and out the edge of your base. While keeping that in place, put hot glue in that channel you made, securing the wire in place. Make sure the hot glue is flush with the flat bottom surface of the base so it sits evenly. The limited width of the hole that the LED's are going through helps keep it in place, so no need to glue those.

Now all you need to do is simply glue your Finished Crystal over the center with the light!

I hope you all enjoyed this tutorial, and please leave feedback!