Here's how I laid it out. I felt pretty confident in what I was doing, so I didn't bother posting it for anyone to review before I drilled holes in the board and soldered it up.
If you're a total crossover noob like I was (am), I'll explain for you what we have here. First, the schematic created and posted by Bill Waslo, over at diysoundgroup.com
My layout uses the same general positioning because it was easier to think about that way. So, following a tip I read somewhere, I created a large grounding strip from a bit of 14g romex I saved from demo. I laid that more-or-less down the middle to give me a convenient place to reach ground. Then , working from left to right across the top, just like in the schematic, I ran the series (in-line) components that lead from the amp input to the board (A+) to the tweeter output from the board (T+). Those components are (in order) the 20 microfarad capacitor, the parallel section of the 1.5 microfarad capacitor and 12 ohm resistor, followed by the 6.2 ohm resister. Feeding off that series set are two branches: the first comes after the first capacitor in the tweeter series and includes a 0.4 millihenry inductor and a 5 ohm resister; the second branch includes a 0.05 millihenry inductor and a 7.5 ohm resister. Each of those branches simply shunts portions of the signal to ground (that's as detailed as I can describe their function, unfortunately)
The woofer portion of the crossover is simpler. It begins at the same (A+) feed from the amp, and includes a 1.5 millihenry inductor in series. That's the big iron core fella - he acts (when in series) as a low pass filter. Branching off the woofer circuit is a single branch including another 20 microfarad capacitor and a 3 ohm resistor. You'll notice that it doesn't look like the last two components of the woofer section branch off, but they do (imagine that you are an electron working your way from the amp to the woofer - once you pass through the inductor, you can go to ground through the cap and resistor, or you can go to the woofer, from the connection at the bottom left of the board. Now you know everything I know about passive crossover network design (almost).
When I went to solder it up, I drilled holes through the board to run the wires through (If you look closely, you can see black sharpie dots). I wasn't sure why this was done, but I found it helped to hold everything in place and make working with the soldering iron easier - on the other side there are no components in your way. I marked the places I thought the holes should go and went and drilled the holes. Then I routed all the wires through and found that a couple things needed adjusting - so I drilled a few new holes. Some of the components have shorter wires and needed to be brought together. The inductors in the tweeter circuit got moved apart because it occurred to me that they were at risk of producing interference. Just now though, it occurs to me that I wasn't thinking about the woofer inductor at all - it may be totally too close to the tweeter circuit inductors. On the other hand, maybe it's not a problem... dagnabbit.
Here's what I did. I hope it's not seriously compromised. EDIT: IT'S WRONG! This picture doesn't match the component layout in the previous image - nor does it match the diagram.
My soldering work is not exemplary, I know. I used a standard rosin-core solder (60/40, 0.062 dia, 1.5 oz) that I bought from RadioShack about a decade ago. I used a 30W electric iron, I bought from the 'shack, that same day a decade ago. Once it warmed up (about 5 minutes), it seemed to work fine. I went ahead and added leads to go to the drivers and binding posts. Maybe that was a dumb idea. It seemed like a good idea to me. I used bits of some 16g wire I had leftover from demo again. You'll see more wood glue that should help prevent my accidentally tearing it apart while trying to install it in the cabinets.
This last photo shows the overall layout of the reverse of the board. You can see the red feed into the board from the amp (was top left in the image of the front, now is top right). The negative feed back to the amp is the black wire connected to the ground strip. The two green wires are negative for each driver, and the white at the top (marked T) is the positive feed for the tweeter.
So, if I didn't mess it up by putting the iron-core inductor too near the air-core inductor, then I'm okay and ready to finish the cabinets and install everything. If I messed it up... well, hopefully someone will tell me.Edited by HopefulFred - 7/7/13 at 11:36am