Most "AI for CAD" tools right now are just fancy wrappers that spit out a STEP file that looks right but is physically impossible to manufacture. As a data engineer who occasionally tinkers with hardware, I've realized that generating a 3D shape from a prompt is the easy part; the nightmare is ensuring that part actually fits into an assembly without needing a miracle from the machinist.

To move from a "cool demo" to a real-world AI workflow, we need LLM agents that can handle parametric constraints rather than just generating static meshes. If the AI can't understand that a hole needs a specific tolerance for an M3 screw, the output is basically digital art, not engineering.

For those trying to bridge this gap, I've found that the only way to get usable results is to treat the AI as a script writer for OpenSCAD or FreeCAD's Python API, rather than asking it to "draw" a part.

Here is a basic workflow for generating a parametric bracket using Python for FreeCAD:

import FreeCAD as App
import Part
Define dimensions for a simple L-bracket

width = 20.0
height = 40.0
thickness = 5.0
hole_dia = 3.2 # M3 clearance
Create the base plate

base = Part.makeBox(width, 20, thickness)
Create the vertical wall

wall = Part.makeBox(width, thickness, height)
wall.translate(App.Vector(0, 0, 0))
Boolean union to merge parts

bracket = base.fuse(wall)
Add a mounting hole (cylinder subtraction)

hole = Part.makeCylinder(hole_dia/2, 20, App.Vector(width/2, 10, 0), App.Vector(0,0,1))
final_part = bracket.cut(hole)
Part.show(final_part)

By forcing the AI to output code that I can audit and tweak, I avoid the "black box" problem of direct Text-to-CAD generators. It's slower, but it doesn't result in parts that break the laws of physics. Plus, keeping the logic in a script means I can version control my hardware designs in Git, which is a sanity-saver for anyone who has ever lost a .step file version.