This idea has been bouncing around in my head for a while now. I wanted an aggressive half round rasp for shaping the handle/fade area. I finally figured it all out in my mind and bought the supplies. I ordered 10 hacksaw blades from ebay for a little over $8. I should have got another 10 because I ended up using 17 blades. I also bought some cheap epoxy and two end caps. I already had the dowel rod and 1/2" copper pipe in my garage.
My supplies. The blades are 18 tpi
I used a dremel tool to cut a slit in the pipe
I used a micro sized pair of channel locks to open the pipe up.
I cut a section off of each cap and filed them smooth. I rounded the edges on everything so nothing pokes your hand when you use it.
A quick test fit
I hammered the pipe tightly on the sides of the dowel rod so it was a very tight fit getting the blades into it. They were held in very tightly on a test fit. I took them back out, coated everything inside with epoxy, and then put the blades back into the pipe. I made sure to push the blades down on the sides so they could follow the contour of the dowel rod. I used epoxy on the end caps and also put a small screw into them to make sure they don't come loose.
After the epoxy set up a little I tested it on a scrap of wood. You can roll it as you push the file and get a nice rounded cut. It does clog up a little but it is very aggressive and removes wood quickly. I am very happy with how this turned out. I can't wait to try it out on a bow.