Make the board itself? I'm not there yet, I'm taking DC circuitry next semester. Afterwords, I hope I have the knowledge of making a board like that from scratch. And replacing the emitter is really easy. But you would have to use some type of thermal epoxy or glue. Or Thermal grease with some type of clamp. Using regular glue would create a thermal barrier and prevent any heat from dissipating to the heatsink.
For me, as a mini mini pocketlight, I use
this:
For quick access, I put it on my keychain, I don't normally have a flashlight on me, but when I need a quick light, I just pull my keys out.
And yes, those Maglites are made by me. But I buy the circuit boards.