Autodesk's free tool for editing and repairing STL meshes: sculpting, hollowing, cutting, combining models and generating tree supports.
Autodesk stopped developing Meshmixer around 2021 and folded some of its features into Fusion, but the last version is still free to download and remains a favorite for quick mesh fixes.
cnckitchen.github.io
Free browser tool from CNC Kitchen that coils a long, strip-shaped STL into a flat spiral and exports a new STL, handy for fitting long parts on a small build plate. You set the inner radius, pitch and winding direction…
blender.org
Free, open-source 3D creation suite for modeling, sculpting, animation and rendering. It's not CAD (no precise parametric history), but it's unmatched for organic shapes, figurines and artistic models, and its 3D Print…
formware.co
Free online tool that automatically repairs broken STL files (holes, flipped normals, non-manifold edges) so they slice cleanly. Upload, repair, download; nothing to install. It comes from Formware, a developer of slici…
