This is a really easy step. We are going to glue a couple of components into the main body. The only real danger in this step is that you'll get sloppy with the glue. Which I happened to do in my tutorial. But no worries, if you use the right glue, you can recover easily.
Here's what we're going to use in this step. The main body, the LED that we filed down earlier, and the yellow dome that we prepared in one of the early steps.
First order of business is to do a test fitting. For my build, I was very lucky to have everything just drop into place perfectly. If the pieces are too big, or too tight, don't force it. Sand down the edges of the dome or the LED. Do not try to sand the body. You'll just screw up the paint.
Mix up a little bit of the two part epoxy, and go to town. Use the same epoxy that I mentioned in the yellow rod step. You don't need a ton of the stuff. I recommend you put a little dab in the bottom of each of the wells, then just push it around a bit to get even coverage. You do NOT need a big glob of glue. Though I forgot to do it in this step, you should take the tip of your x-acto blade and scrape up a little bit of the paint in the places where the glue is going to go. This will give the glue a little something extra to bite into. It's not super important, but it can only help.
Here's what the pieces look like installed. You can see I globbed too much glue, and ended up with a drop just to the right of the LED. The good news is that once the glue dries, it will snap right off the painted part without causing any trouble.