Step 4: Lamp
Something as simple as a light bulb doesn't really care if it's powered by AC or DC power, as long as the voltage is right. We are using a 12V battery, so there's no problem repurposing this bulb.
The lamp will take the place of the fan. Hold up the bulb to circular grate where the fan was. Mark how much space the bulb will take up. It's round, and so is the fan, so it should fit OK, but not all the way back into the case. (A different size bulb might fit flush, or even INSIDE the case!)
Using the side-cutters or a tin-snips, snip the tin fan grating to make the bulb fit. You could also use a Dremel or other cutting tool.
Test-fit the bulb, but don't permanently attach it yet. First, we will want to wire up the lantern.