Saw something like this angled chamber brush for a Winchester 1873 on eBay but thought I'd try making one for free. Took about ten minutes.
1. Take the cheapest most worn-out 1/4" flat blade screwdriver you have laying around.
2. Heat with a propane torch until it glows red.
3. Bend it about 45 degrees or a bit more in a vise or with pliers.
4. Heat the screwdriver blade to red and let cool to remove any temper so you can drill and tap.
5. Drill a #29 hole in the blade; thread with an 8-32 tap.
6. Grind off the corners of the blade so it won't scratch anything inside the rifle.
7. Screw in bronze brush of your choosing.
If you have some 1/4" brass rod around, you could use that instead.
I thought the ready-made screwdriver handle would be nice to grip, and it was a throwaway I hadn't touched in years. I might dip the end in Plasti-dip to rubberize it, but it does the job nicely as is.