What to check before you download a generated 3D model

Why check at all

The model is generated from your description, so the most common problem is not a bad model but a description that missed something: a taper, a cable in the way, a wall the part has to clear. The checks below catch those in under a minute, before the printer spends two hours on them.

1. The assumption summary

Every render comes with a short list of decisions: "2 mm walls, 0.2 mm press-fit clearance on the shaft, 3 mm standoffs, 0.5 mm chamfer on the base, printed open side up". Read it. If you print PETG and know your printer runs a little wide, "0.1 mm more clearance everywhere" is a one-line fix. If the part will take load, "2.5 mm walls" is another.

2. The dimensions readout

Length, width and height are shown under the model, along with volume. The volume is a sanity check on wall thickness (a box that reports far more material than expected has solid walls) and a rough guide to print time. The dimensions tell you whether it fits the bed (220 mm is the default virtual bed; say your bed size if it is smaller) and the space it is going into.

3. Tap the mating faces

Overall size rarely matters to the tenth of a millimetre. The hole for the shaft does. Tap the inside of a hole and the readout shows its diameter; tap a slot and it shows the width; tap the floor of a pocket and it shows the depth. The dimensions panel lists every named number in the model as well, so you can type the one you measured with callipers directly.

4. Look from underneath

Orbit below the bed. Three things to look for:

• A flat bottom. The largest flat face should be on the bed. If it is not, "lay it on its back" or "print it on the long side" reorients the part.
• Floating geometry. A feature that starts above the bed with nothing under it will not print. The AI avoids this, but a strange request can produce it.
• Overhangs. Faces steeper than about 45 degrees from vertical need supports. A chamfer instead of a horizontal step usually removes the need; ask for one.

5. Wall thickness

Walls under about 1.2 mm print as a single fragile perimeter or not at all at a 0.4 mm nozzle. The AI's default is at least 1.2 mm and usually 2, but if you asked for a very thin feature (a living hinge, a flex clip) check that the number is deliberate. Wireframe mode shows the geometry the slicer will see, including any sliver walls where two features nearly meet.

6. The ghost

After an edit, the previous version is drawn faintly behind the new one. This is the fastest way to confirm that "lip 5 mm" changed the lip and nothing else. If the ghost shows the whole part shifted or a hole moved, say "keep everything else where it was" and the AI re-applies the edit narrowly.

7. Multi-part files

A box and its lid, or a test coupon and the full part, are laid side by side. In a 3MF they are separate objects you can print one at a time; in an STL they are one object. Pick the format to match how you will print.

Then download

STL or 3MF, 10 credits. If the print reveals something the checks could not (the shelf was 18 mm, not 16), the fix is a sentence and the corrected file re-downloads free. The checklist is not about avoiding every reprint; it is about making sure the first print teaches you something the screen could not.