30 centimeters

First you need to draw a layout on a sheet (preferably in a cell) on a scale convenient for you.

Then you need to choose an even place on the site and place the contours of the future pantry. On four sides in the corners you need to dig holes with a depth of about 30 centimeters. Then cut the profile pipes in accordance with your drawing. Connect parts with each other using electric welding. When the frame is ready, you need to weld the doors to it on the hinges.