Working as a mechanic these days, we tend to work with epoxy a lot. Everything is plastic and whenever you try to fix something, you almost always end up breaking something else in the process. For example, if you're trying to replace a defective stereo, it's likely you'll break a retaining tab off the front dash bezel. It's become a fairly common occurrence.
Working with epoxy is fairly simple and straight forward. Just a few things to remember.
1: Prep the area ahead of time. Sand it down with some 220 grit paper, then use acetone to remove any oils or residues.
2. Mix the epoxy 50/50 with the hardener. Once mixed thoroughly, you only have a few minutes to work with it before it starts to set.
3. Once you have the area epoxied, leave it alone. Don't touch it, move it or play with it. Let it harden for at a minimum of 24 hrs.
Also, a little known fact with glues like epoxy and especially superglue, is that it's actually the moisture in the air that makes it harden. "The reaction is caused by the condensed water vapour on the surfaces (namely the hydroxyl ions in water). The water comes from the surrounding air."
SOURCE. So contrary to popular belief, the less humid it is, the longer it will take to set.