well, I bought my spine tester...
I bought one of the cheapie ACE ones that hangs on a wall or cabinet because I figured by the time I had all the stuff found to make one, I would have been better off buying it anyway...

Dean Torges told me once that, "..a traditional archer will study a $20. product fifty different ways for two hours, then spend $200. at Home Depot for the tools to build it..."

so be that as it may...

you'll want to rotate your shafts in the tester to get your grain and spine oriented the right way... when you find the axis where the spine is highest, mark the arrow vertically for nock orientation