Piper, Here is my version of a James Hill spine tester, also made with scrap wood. As per Art Butner I used a large diameter bolt for the weight. As you can see it pushes down through eye bolts rather than pulls down like a suspended weight. I'm not sure if the direction of deflection matters or not.
Also from Art, the adjustable upright. The one on the right has a slot in the wood where the bolt goes through and a wing nut for quick adjustment. I think I got my dial indicator from Grizzly.
The drop bolt weight has a copper plumbing sweat fitting forced over the hex head with lead added inside to make up the 2#. I weighed the components using lead shot until I had the 2# then melted the lead shot and poured it into the copper fitting.
I used skateboard bearings for the arrow shaft to rest on when spine testing.
I also have a suspended weight that I use. It is a small metal PVC pipe cleaner can with a cup hook in the lid. I added lead shot to it to make up the 2#.