4mm slot when fitted before the stem and it's fairly snug then, so it won't be much less than that when tightened, and cold rolled based upon your description.
Are there better bike-specific choices, or should I head for the model railway shop?
Strictly speaking, you hold the workpiece against a moving abrasive for linishing, but you can get the same effect on solids of revolution by spinning the workpiece and holding the abrasive.
4mm slot when fitted before the stem and it's fairly snug then, so it won't be much less than that when tightened, and cold rolled based upon your description.
Are there better bike-specific choices, or should I head for the model railway shop?
"Linishing": every day's a school day!