#Replace face

Hands a surface back to the body: the picked faces are removed, the surface takes their place, and the body is whole again.

#Why

This is the far end of the bridge into the design layer. The loop is: take a face out ("Copy face"), reshape the surface on its own, hand it back. The node lives in the timeline, not as a layer on top of the model, so anything can be built below it: fillets, holes, a shell.

#How

1. Press Replace face.
2. Click the body faces you are replacing.
3. Click the surface — it is a separate sheet body, hard to confuse with anything.
4. Enter to apply, Esc to cancel.

#Worth knowing

• The boundaries must match. Replacing a face means the surface stands on ITS edges, not roughly in the same place. A common mistake: the top of a shelled part is a RING as wide as the wall, while the patch is stretched across the whole opening. The ring and the lid are bounded differently, the inner loop is left unpaired — and the node turns red. Build the patch on the same edges that bound the face being replaced.
• Capping an open box is a different job. A shelled part is already closed: the top is a recess in the material, not a hole in the surface. A lid there adds material — that is an extrude or a thicken, not a face replacement.
• The surface must close the opening. If a gap is left after the faces are removed, the node turns red and says how many edges are left unpaired, and the part stays as it was. "Almost a solid" is never handed on: further down the timeline it would behave like garbage.
• Faces are stored as a description. Say "all faces of this feature" and the node keeps replacing exactly those after the base changes, not yesterday's numbers.
• Both inputs are absorbed. One part is left on screen, not a part plus a surface over it.
• A lost target is an honest refusal. Nothing "similar" gets replaced instead: putting design work in the wrong place silently is worse than not putting it at all.