I can write 3d a program kernel.
Reading and record in dxf will be used only.
Without use vla -*!!!
For example:
Select of sides, edges, vertex in 3dSolid (grread)
Creation 3dSolid (entmakex)
Moving (entmode)
Rotation (entmode)
Mirroring (entmode)
Offset (entmode)
Union (entmode)
Subtraction (entmode)
Intersection (entmode)
Transformation USC (entmode)
Moving of sides (entmode)
Moving of edges (entmode)
Moving of tops (entmode)
Change of radius's faces (entmode)
Change of initial region for Extruded 3dSolid (entmode)
Purge for 3dSolid (entmode)
Possibly, more many various functions.
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PS. But I, cannot do similar work free of charge. This very big task...