You need to translate the plot so:
data = load(assetpath("brain.stl"))
fig, ax, plt = mesh(data)
translate!(plt, 0.0, 0.0, 10.0)
If you want to translate via an observable you can do:
onany(x, y, z) do x, y, z
translate!(plt, x, y, z)
end
There is also an option to give a plot a transformation like so:
fig, ax, plt = mesh(data, transformation=Transformation())
But this all bitrotted a bit and isn’t that user friendly right now… You can have a look at the constructors for Transformation to see how to pass it the translate Observable…