This was my first speaker project, way back in high school. I didn't know a lot about speaker building at the time, so I went with a simple open-back configuration. Speakers are Celestion V12-60's. They are a little warmer than the standard Vintage 30's, which works nicely for me. The choice of speakers, like basically everything else about the cabinet, was arbitrary -- Guitar Center happened to have them on sale when I went to buy speakers.
Not having a cabinet to measure from, I just winged the dimensions. As a result, the cabinet turned out much larger than most commercial offerings. I thought at the time that I needed to space the drivers out or it would weaken the baffle. Unfortunately this increases the cabinet's tendency to beam at higher frequencies, and the cabinet is somewhat more directional than the standard designs I've played through.
Even with all the mistakes (musicians may notice I even mounted the plastic corners incorrectly), the cabinet sounds pretty good. Call it a happy accident, but it records well and has plenty of volume for any gig I've ever had to play. I'm glad I went with the open-back design; it has nice airy sound that can't be replicated by sealed cabs.