Start the SimCellDesigner. Deselect "Show Ruler".

Increase the Compartment Width to 50, the Height and Length to 30. Click "New Cell". Then "Center Cells".

Increase the of the cell by moving the Protrusion Size slider until the cell has a volume of 6859 cubic microns (with the Grid Constant set to 1 micron (default)).

Move the cell out of the center to the left side of the compartment by moving its x Position slider all the way to the right. (The cell's volume will decrease since only the volume within the compartment is taken into account -- we will restore it later.)

Click "New Cell" again. Move the x,y,z Position sliders of the second cell into the center.

Increase the of the new cell by moving the Protrusion Size slider until the cell has a volume of 6859 cubic microns (with the Grid Constant set to 1 micron (default)).

Click "Center Cells".

By changing the x Position slider of one cell move the cells together until their contact covers a width of about 19 volume elements.

Select "Show Ruler" and draw the ruler line somewhere in the compartment by clicking once, then moving and clicking again.

Move the ends of the ruler until the ruler stretches from one face of a cell to the other face.

In the text field next to the "Rescale Ruler Length to" button enter 30. Click the "Rescale Ruler Length to" button. Now the diameter of the cells is 30 microns. Their volumes should be around 13600 cubic microns.

Now, we will define the regions needed for the specification of the initial biochemistry (which molecules go where with which concentration). Switch the Edit Mode of the first cell to Regions and click "New Region". Move the region (half-transparent shell around the cell) until it covers only the first cell.

Similarly for the second cell.

Set the Name for the first Cell to Cell1, the second cell (you may have to swich the Edit Mode back to Geometry) to Cell2. Click the "Save" button and save the configuration to "TwoCellContact_static.geo" -- preferentially (but not necessarily) into the same folder as the Model.

Move the cells apart again until their distance is two volume elements. (Disable the ruler again to avoid inadvertently changing the scale.)

Click "New Protrusion" for Cell1. This will generate a second source of volume for the cell that you can move independently to create a small contact between the cells. You will initially not see it as it is hidden in the main protrusion of the cell. Move it by moving x Position slider of the new protrusion. Note, that the volume of the cell changes as soon as the second protrusion leaves the main cell body.

Make sure the new protrusion just touches the other cell. You can check this by switching off the other cell's display.

Adjust the Region of Cell1 to include the new protrusion.

Check that the Region of Cell2 covers the entire Cell2.

	Note
	Since regions are handled cell-wise it would do no harm if Celll1 would be partially covered by the Region of Cell2. If you increase the size of the Region of Cell2 until it seems to wrap parts of Cell1 and then switch off Cell1 you will see that the Region avoids the space claimed by Cell1.

Click the "Save" button and save the configuration to "TwoCellContact_small_dynamic.geo" -- preferentially (but not necessarily) into the same folder as the Model.