Many 3D content creation tools such as Blender [0] have SDF [1] (e.g. metaballs in Blender) and CSG [2] (e.g. boolean modifier in Blender) features. But these are rarely used as they can only define volumes, not surfaces. And we are usually interested in surfaces for assigning textures and materials. Thus, polygons / meshes and curves / splines dominate the industry.

[0]: https://www.blender.org/ [1]: https://en.wikipedia.org/wiki/Signed_distance_function [2]: https://en.wikipedia.org/wiki/Constructive_solid_geometry

The two best SDF modelers in existence are MagicaCSG[1] and Adobe Substance Modeler[2]. There are also a few others, like Womp, but those two are the most feature-complete. Blender is also adding them as part of geometry nodes, and there is also an add-on that is working on adding SDF for hard-surface.

[1] https://ephtracy.github.io/index.html?page=magicacsg & https://www.patreon.com/magicavoxel

[2] https://www.adobe.com/products/substance3d/apps/modeler.html

Blender Geometry nodes supports SDF modelling. It's just not a widely known or used technique. But it's super powerful.

Plasticity (https://www.plasticity.xyz/) is a new-ish one that looks neat, but I wish it offered a lower-price entry point.

Adobe/Substance3D Modeler

TinkerCAD.