I built a >1W handheld laser using a diode from a Casio laser projector. These diodes cost about $50 each and can be found for sale online. My driver is a buck-boost topology using a TPS63020 IC from TI. This driver tested to be 82% efficient into my laser diode at 1.25A. At 1.25 A, my laser diode has a forward voltage of about 4.5V. My driver features reverse polarity potection, undervoltage protection for lithium batteries, and output overvoltage protection. Photos of my driver board unpopulated are here and here.
This housing was machined by laserpointerforums.com member Ehgemus. It is a combination of polished and sandblased aluminum.
I stuck the driver on a block of copper using some arctic silver for testing. It never got more than warm even at 2 A into my test load.
I used 26 AWG silicone insulated wire. This wire is very flexible and does not apply much force to the leads of the laser diode.
The driver was glued to a brass heatsink using thermal epoxy. This heatsink arrangement is very good at dissipating the heat that is produced in the driver. The heatsink is also a slight press fit into the housing so nothing can vibrate around.
Schematic of driver. Click to enlarge.
These batteries are 26650 size and rated at 4 AH. They are 3.6 V nominal LiMnNi batteries from batteryspace.com. I made a holder for charging them from a C size battery holder. I charge them with a bench power supply set at 4.2V with a current limit of 4 A.
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See other projects on my main page at rfhv.com