Here you go:
1. My first Emisar D4 lighted metal switch mod
2. Updated Emisar lighted metal switch with better lighting
Here’s a post that provides extra detail on how to make the metal button. This one is not lighted, but the process is the same. For the lighted version use a slightly smaller button so the silicone has a gap at the edge. And it is necessary to add a raised switchboot retaining ring since the stock ring is too flat:
3. Metal switch mod with no light, but more detailed instructions
Note that if you have the raised-ring Emisar D4v2 you may be out of luck. You can shave the boot down and glue a metal disk on top as-is, but at least on mine, I found that retaining ring impossible to remove.