This instructable aims to show you how to cut any type of disk to a desired shape. It is particularly useful in cutting down cheap 12cm DVD-+R 's into more expensive (can be up to 10 times more) 8cm DVD-+R disks. The technique shown here works with all disk types. The video below shows us cutting a music CD into a heart shape, and also illustrates the basics of cutting 12cm disks into 8cm ones. The actual cutting of a disk (and the guide) can be seen here:

Step 1: What You Need

1. A Dremel or similar cutting tool. See http://en.wikipedia.org/wiki/Dremel I use a $20 cutter with adjustable speed
2. Pointed cone cutting tip (show below)
3. A hard surface to cut your disks on (like a tray)
4. Some practice disks
5. The real disks
6. A filtering mask (if you are ultra careful you won't want to breath in any plastic/aluminium dust from the disks)
7. A stencil (for the desired shape) and a marker
8. A steady arm/hand
9. Patience

Step 2: Some Information

The following was lifted from Wikipedia:

A compact disc is made from a 1.2 mm thick disc of almost pure polycarbonateplastic and weighs approximately 16 grams. A thin layer of aluminium (or, morerarely, gold, used for its longevity, such as in some limited-edition audiophile CDs) is applied to  the surface to make it reflective, and is protected by a filmof lacquer. The lacquer is normally printed directly and not with an adhesivelabel. Common printing methods for compact discs are screen-printing and offset printing.

Hence we know CD's are made from plastic and a thin Aluminum layer. This means we can cut and shape disks by using a suitable cutter with a high enough RPM (revolutions per minute)

Disc shapes and diametersA Mini-CD is 8 centimeters in diameter.A Mini-CD is 8 centimeters in diameter.The digital data on a CD begins at the center of the disc and proceeds outwardsto the edge, which allows adaptation to the different size formats available. Standard CDs are available in two sizes. By far the most common is 120 mm in diameter, with a 74 or 80-minute audio capacity and a 650 or 700 MB data capacity. 80 mm discs ("Mini CDs") were originally designed for CD singles and can hold up to 21 minutes of music or 184 MB of data but never really became popular. Today nearly all singles are released on 120 mm CDs, which is calleda Maxi single.

Hence, we can cut away the outer parts of disks which have no data written to them (provided we have not used the entire disk space)

An easy way to make sure you cut safely is to look at the shiny side of the disk and see how much of the area is darker or shaded. This shows the area of the disk onto which data has been written. The rest of the disk can be cut away.

Step 3: Preparation

Please first practice on 3 or 4 disks you have lying around. Cd's from newspapers or magazines make good practice disks. Remember, practice makes perfect!

You need to find the right shape to cut a disk. Disks are best cut into shapes which have rotational symmetry. These will also play better in some drives, as they will not make any excess vibrations. In the video, I cut 2 cds, one into a heart shape and another into an 8cm disk. The heart shape will not fit into a conventional PC CD-ROM drive, but the 8cm disk would. The images below give you some indication of what is required, but you can (and should) experiment with other shapes.

Also, keep in mind that the more you cut away, the less data you can store on the disk. I also recommend you first write data to your disks BEFORE cutting/shaping them.

Step 4: Cutting Technique

Technique is very important when cutting disks (as you may have seen from practice). You need to keep a steady hand and cut slowly. Also make sure you keep your cutting tool at a consistent depth so that you produce an even cut. Below you can seem me cutting a heart shape. Cutting tips include holding the cutting tool steady and moving the disk along the path you want to cut. Watch the video and you will see what I mean. Also, use a high RPM, of about 20 000. It is also helpful to hold the disk vertically. Since the cutting tool spins in a clockwise direction, you want to make sure you are cutting away from the center of the disk. This is so that the disk is cut smoothly and the outer bit is rough. Through practice this will become easier to master.

Step 5: Cutting 12cm Disks Into 8cm Disks

This is also a nice money saver. Many people use 8cm disks for video cameras and the Game Cube console. Despite their size, they are considerably more expensive than their larger 12cm counterparts. Here's how to cut 12cm into 8cm:

1. Use a suitable stencil for your 8cm disks. I used a coffee/tea mug.
2. Position the stencil in the center by marking the disk 2cm in (shown in video)
3. Using a marker, draw around the stencil
4. Cut from the outside of the disk in, making sure you don't touch your marking.
5. Once you've cut the basic shape, use another tip for your cutter to smooth it off.

Please practice with some old ones first. Once you get the hang of it, its actually quite easy.

Step 6: Conclusion

I hope you liked this instructable. The key ideas presented here can be used to make all sorts of shapes for disks. Here is a nice image of some interesting shapes.