Reaping the rewards of painful learning

"An expert is a person who has made all the mistakes that can be made in a very narrow field." -Niels Bohr
I made a lot of mistakes on the laser, and now I've got a pretty good handle on it. Yesterday I made a lot of progress on the laser and my acrylic Z axis, where do I begin?
Well first I quit my job on Friday, so I've had a lot of time to work on this project. It's still feel a strange feeling to not be busy doing something I don't like. I like this personal fabricator.
My parts from Makerbot came yesterday also after 4 weeks. I asked one of the founders to throw in two boards to make up for the mistake by throwing in two bare PCBs for the stepper motor controllers. They threw in two free PCBs, but they threw in the wrong PCBs!
Back to my Acrylic, I made this "capture nut" and press fit assembly to attach vertical and horizontal pieces. I made the gap to attach these 2mm larger than the material thickness; that was loose as a goose. I later made the gap the same dimensions as the material thickness and that works beautifully. It is a very tight fit, I had to do a little filing but once the pieces went in they were not going anywhere. I had a fear of the capture nut weakening the material, but 1/4" acrylic is very strong.

The picture here is the Z base with two press-fit supports attached using no capture nut, there is a nut in one piece but no bolt.