#Shell

Key H. Select the body, click the face to be removed, set the thickness, press Enter.

The body becomes hollow: material is taken out inside, the remaining walls get the given thickness, and the picked face disappears — that is how the cavity opens.

#About the thickness

The thickness goes inwards. A thickness too large for a narrow spot leaves no material and the operation fails — that is not a fault of the program, such a wall simply does not exist.

#Order in the timeline

A shell goes after the main shape but before the small fillets: then the fillets land on both the outer and the inner edges. Put the shell after the fillets and the inner edges stay sharp.

#A hint

If you need an even wall not over the whole body but along an outline, look at the sketch offset: it works with a flat outline and is sometimes simpler.