Testor's plastic model glue DON'T USE... I tried it takes forever to cure, yet I was able to snap apart the pieces. as well, regular epoxy and CA. Now I have yet to try the Plastic Weld Epoxy. My concern with that is possibly leaving a very noticeable glue line. I hope this helps a little.
I use Gorilla epoxy. I didn't have any problems at all with it and the pens I still have, look just like when I finished them.
If I make any more pens, I will continue to this epoxy.