You can build a simple laser pointer using inexpensive parts and save tons of money versus the cost of buying one new. Keep in mind that building a laser pointer can have drawbacks, though, and make sure you keep the law in mind.
Consider the legal limits.
Legally, laser pointers have a 5mW limit. Any laser pointer you have over 5mW is in violation of the legal limit, and you can be prosecuted for having a more powerful laser pointer. Home laser pointers almost always exceed the legal limit, based on the materials and power supply used, so be careful to tone your laser pointer down. Powerful laser pointers can also cause injury, so be extremely careful when you use it. Do not aim the pointer at another person, do not look into the pointer and do not let children handle the pointer.
Start with a case.
You need a case for your laser pointer. Even an Altoids box works, and keep in mind that a metal casing is most secure. Simply drill a hole in the top of the casing for your switch, and a hole in the side of the casing for your laser, and you're ready to proceed with the inner workings. You can also use a mini Maglite flashlight for your laser pointer casing.
You need a laser diode.
The diode is the part of the laser pointer that emits the light. Infrared laser pointers and blue laser pointers are all made using a single diode. Green laser pointers, on the other hand, require a different construction method that's more difficult to achieve at home, so you're better off buying one instead of making it yourself.
To get a laser diode, you can take one from a DVD burner or CD-ROM drive or order it online. If you want to extract a laser diode from a DVD burner, you'll need to disassemble the entire drive. Keep in mind that removing the diode renders the DVD burner unusable. Unscrew the DVD burner housing to expose the inner workings of the DVD player. The laser diode assembly moves back and forth on two metal rails. Remove it from the rails, and unscrew all the tiny screws holding the assembly together. Then you can extract your laser diode.
Insert the diode into the laser casing.
You can get the casing for your laser diode from Aixiz. The casing holds your laser diode and enables you to build it into the laser pointer. Aixiz laser casings come with diodes installed, but they're small diodes and may not be powerful enough for your needs. Gently remove the existing diode from the Aixiz housing, and insert your new diode. You may need to solder longer pins onto your laser diode to make a connection with your power source.
Add your power source.
Finally, you need a power source to power your laser pointer. You can use a simple battery pack that you can pick up at any electronics store, such as Radio Shack, or you can use regular batteries in the existing casing of a Maglite. If you're using a custom power source, make sure you wire the diode up correctly; reversing the polarity can damage your diode. Connect the diode to the power source, slide it into your casing and enjoy your laser pointer.