I started working on a patternmaker's saw that I've been meaning to make. I first saw one at Leif Hanson's site.
I cut mine from a saw I got at a junk shop.First, I cut out the basic shape; 7 1/2" by 1 1/2". It also has a pointed nose to reach in awkward places. Using the template for 15 tpi,(on the "adding teeth" part of the Backsaw Project) I started cutting small grooves with a saw file. My best advice is to read this entire article, as it has the basic operations illustrated in it.
Later when I am further along on the teeth, I will do a better post on how exactly I did it.
For the handle, I took the provided photo, and scaled it so it was large enough. Make a prototype, and then see if it fits your hand well. Keep in mind when the handle is rounded over, the handle will feel slightly larger. In this photo the prototype is about 1/2' too long.