FreePrimitive Geysers and Mud Vents - Prehistoric Scatter Terrain
MyMiniFactory
8 model
Free
FreePrimitive Stone Hearth - Tribal Cooking Fire Scatter
MyMiniFactory
FreeBasic Primitive 3D Shapes - Cube, Cylinder, Cone, Tube, Pyramid, and Sphere
Printables
FreeTerrain - Primitive Shelter
Thingiverse
FreeBashar's Primitive Spacetime Antenna Coils
Thingiverse
FreeYoung Cavegirl with Stone Prop
Sketchfab
FreeChamfered primitives for OpenSCAD (Also: Wedges)
Thingiverse
FreeSimple basement
Sketchfab