Turning a detailed surface into a thin-walled walled shell

Hi. I’ve created a character surface that looks good on the outside. Now I need to turn the surface into the outside a thin walled shell suitable for 3D printing and of course the inner surface needn’t be as detailed as the outer. Is there any effective way to do either of those? Does anyone have any experience with 3D printing of thin-walled character meshes or character meshes at all? Thanks.