Did you make it by hand? And if so, how?
I usually cook the bovine shin slice in my soup, leave the beef in there and give the dog to the bone.
When he had finished his meal I took the shin and cut one rectangular piece with a metal saw. The rest was filing, sanding and drilling by hand.
Now you just need to test-roll it 100,000 times to make sure it rolls true.
I did a hundred times and it was good enough.