If you just want a domed pin, not swelled or peened. Chuck your pin in a drill, a drill press works best, and turn it on, and using a file, round the end of the pin slightly, and then finish with sand paper up through the grits to your desired finish, and cut to the proper length, and do the other end, this accomplishes the same result as a head spinner tool. I do this on all of my pins for use in antler. If you want to peen your pins, lightly taper your holes. With a small ball peen hammer, very carfully use light taps, in the center of the pin, this will swell it out evenly in the tapered hole, and get tight. Make sure the back side of the pin is solid against something like a small thick steel block, I use some 3/4" x 2" about 3" long.
I don't recommend peening pins in wood, bone or antler as it creates pressure that can cause it to crack. If you want more strength than a straight pin in scales of wood, bone and the like, use bolts.
Hope this helps.
Dale