This article show a way to make very strong washer bars from flat steel using a hacksaw, some files and sanding paper. The process is straightforward but takes quite a bit of time. The finished washer bar will have a shoulder inside the washer which prevents them from moving sideways. The thicknening that the should implies also makes the bar much more resistant to bending.
This is another method of making washer bars. The first method was essentially the same, but lacked the shoulder. and was thus somewhat simpler.
The process step-by-step Edit
First mark the rough outlines of the bars to a flat steel bar:
File the upper surface of the bar round and polish it with sandpaper:
Make cuts using a hacksaw to the edges of the bars as well as at the bars' shoulders:
Saw the shoulder to the correct form:
Round all edges, in particular those that will contact the spring cord:
Polish the entire bar using sandpaper of increasing fineness:
Finally adjust the width of the shoulder so that the bar fits inside the washer: