This replaces the foam gasket thing that goes between your plastic speedometer and the part of the handlebar clamp that it sits in.
Since it's been ~40 years and actual Honda part has been out of production for a while now, but to be honest I couldn't even find a part number for this at Ronayers.com or anywhere else. This may work for a CM200 as well, as long as it has the same speedo.
In any case, this will only really work if you use flexible filament (TPU). I am not amazing at cad, and this speedo has subtle curves and tapers to it, even though it just looks like a rectangle with rounded corners.
I guess you could print it in PLA and just dip it in hot water before fitting it onto the speedo. This would be more of a spacer than a gasket, but it would at least keep your speedo from rattling around.
Print settings:
The author hasn't provided the model origin yet.