This is a rather cheap handheld 5 milliwatt laser pointer I made that runs off C batteries. It is kinda bulky though (about 7.5*7.5*5 cm), but it still comfortably fits in my hand. I will apologize in advance for the fact that I made this instuctable after I was done making the laser.
Disclaimer: I am not liable for any stupid things you do while building this or while using this.
Step 1: Tools and Materials
You will need:
1x Rocker Switch $ .30 http://www.taydaelectronics.com/electromechanical/switches-key-pad/rocker-switch.html or $ 3.00 http://www.radioshack.com/product/index.jsp?productId=3016149&filterName=Type&filterValue=DPST
1x 3x2x1 Project Box $ 2.70 http://www.radioshack.com/product/index.jsp?productId=2062279
1x 5 mw 650 nm 12x30 mm laser diode $ 5.00 http://www.mfgcn.com/
2x 1.4" female quick disconnect solderless connector
1x 2 C Battery Holder $ 2.00 http://www.radioshack.com/product/index.jsp?productId=2062240
The total cost comes to around $10.
Hot Glue Gun
Wire Cutter, Crimper, Stripper
Step 2: Drill Holes.
You will need to drill a hole for your laser diode with a 15/32" drill bit on one of the 1*2 sides. On the other 1*2 side, drill a hole for your switch. I used a DPST switch from radioshack that required a 3/4" drill bit. If you buy from tayda, you will need to drill two 5/16" holes and then use a metal file to make the switch fit. Finally, on the 3*2 side without the screws, drill a small hole close to your switch for the wires to pass from your battery holder to switch- I used a 3/32" drill bit.
Consult the picture if you need any help.
Step 3: Solder
Solder the positive (red) wire from your laser diode to the positive wire from your battery holder (you could also do negative to negative). Make sure that the wire from the battery holder has passed through the 3/32" hole before you solder- otherwise you won't be able to put the laser diode in the project box.
Step 4: Add Quick Remove Female Connectors.
Crimp the two connectors onto the two negative wires (or positive if you soldered the two negative wires). Then you put the connectors onto the battery terminals. It makes your job a lot easier if you crimp the wires on first. Also, if you have a screw on switch like me, you should screw the switch in and then put the connectors onto the battery terminals.
Step 5: Secure Laser Diode, Switch and Battery Holder.
Now you need to secure the laser diode, switch and battery holder using hot glue. I didn't need to secure my switch with hot glue because it was screw-in, but if you don't have a screw-in one, you will have to glue it on. If you do, only glue on the inside of the box, because it gives a cleaner product. The laser should be secured from the inside only to make a cleaner product, and it shouldn't protrude out of the box. The battery holder should be glued on the side without screws.
Step 6: Finished Product.
Once you screw on the plastic top of the project box, you will have your finished project.