Paper tuning isgood way to tune your bow. Bare shaft tuning is too. Paper tuning is shooting through a sheet of paper, and evaluating the tear. For instance, if the tear is up, you need to lower your nocking point. Opposite if it is down. It's pretty simple, you just have to know how. Go to www.eastonarchery.com and download their tuning manual. Lots of very good information in there.
I have made my own spintester. It's pretty easy. I took two pieces of 1/4 inch plywood, about 12 inches long and 6 inches wide. In one of the sheets, I made 2 slots, just wide enough to get 2 ball bearings in without them having any room to move side to side. It is ok that the bearings are touching. I made one slot 1" from the front, and one slot 1" from the back. The size of the slots will be dependant on what size ball bearings, or marbles you are using. Then, screw the two pieces of plywood together face to face, and that's pretty much it. You can use anything, like a box, to set that on for some elevation. From there, you lay the arrow on the bearings and spin it, looking for any wobble.