Lazer pens or jigs do very well for alignment whether it is for the fresnal len or any of the opening in the case. Do a search for lazer or jig and the posts should show up for those two with pictures. Nothing beats them for me.
I did use a laser to do all the alignment and drilling and it was still off. I have searched and was just wondering if once you guys have used a laser or what ever else if you still have a way to make sure things align. If you shine the laser into the frenzel it dang near blinds you. There has to be a better way.