I snagged a clear 2x4 from work the other day for the stretchers of my framesaw, and first rough cut a length about 40 inches long. I planed it a little to smooth and even out the surfaces. Then I marked off 1.5" all around the four sides, and clamped it upright (checking for level) to the front of my bench. Then I used my cheap Japanese crosscut saw to rip down the lines. I would lay the saw flattish on the face and draw the kerf down the line, then do it on the opposite face, then clear out the wood in between. This way the saw tended to (but didn't always) follow the kerfs, staying straight in the cut.
You may notice that my batten is clamped at the end of my bench because in it's usual place the board I was planing would hang off the end. This worked well, and saved me having to drill out holes to accept the pins on the batten.
For the Maple arms (made from a 6/4 quartersawn Maple board), I first squared the edges, then marked off the same 1.5" lines and ripped. This time I used a combination of my cheap crosscut saw and the rip side of my cheap Ryoba. I hate that the perfect tool for the task at hand is so often the one that I'm building. It took me almost an hour to make my two rip cuts through the Maple. I could have scrubbed the 3/4" off the side of one of them, but I didn't want to waste the wood.
Just for fun, I decided to do a rudimentary strength test on the Maple bars. I placed a stool near my bench and used a Maple bar to span the distance, with only about 3/4" at each end. I put my full 190 pounds on the center of the bar and bounced up and down, with no noticeable flex. I think these will be fine for the saw. When I performed a similar test (with the stool moved farther away) with the mystery wood bars, they were also very stiff (though not quite so). This saw will probably end up being a little overbuilt, but with my history of breaking tools, I'm not concerned about it. Next move is to make the hardware!
As a sidenote, this morning I ran in an "un-race", the 42nd Tradition Run 5k with my crazy Canadian friend graham. I'm the one with the green hat. We elected to run back down the course for a nice round 10k.