https://km-3d.com/produkt/smooth-boolean-plugin/

SmoothBoolean is a 3ds Max plugin for creating smooth transitions between ProBoolean meshes. No need to spend hours on cleaning messy topologies created with boolean cuts anymore. If you just want your 3d models to look great on the renderings or you need to bake something for games, then you don’t have to waste your time trying to model fancy Sub-D meshes. This plugin is a real 3ds Max modeling game changer. After buying the plugin you will get free updates for every next version of it.