Based on my reading, you can design speakers without a computer. Heck, people been doing that for dozens of years.
However, it seems like a lot of education and real world experience are required if you decide to skip the computer. I ain't got that going for me.....
So it looks like some software will help a lot... I was initially very excited to learn about Speaker Workshop (http://www.audua.com/), but there are a LOT of people who express frustration getting it to work in a repeatable manner. I think that free software is awsome, but not if it causes me to loose any of my limited hair supply :)
So, I started hunting for software. Ideally, I would like to spend as little as possible for a program that will assist in both the speaker measurement, crossover design, and box design subroutines. I also want to demo the product first, if possible. There are several packages available, but I have narrowed my choices down to ...
LspCAD - http://www.ijdata.com/
SoundEasy - http://www.interdomain.net.au/~bodzio/
ARTA - http://www.fesb.hr/~mateljan/arta/links.htm
Praxis - http://www.libinst.com/
Further review and research (i.e. googling) has caused me to steer towards LspCAD - the standard edition can do the basics, including some nifty crossover stuff... however, it looks like ARTA may perform the measurements a bit better..... sigh... If LspCAD can't do the measurements well, then its $200 for LspCAD Standard and upwards of $100-$120 for ARTA - that is a lot of bread.
Both LspCAD and ARTA have demo software available, so I have downloaded both packages.