How to create a grid with spacers

Daniel,

Based on the IMG shared (please use the Insert Photos button at the top of the Reply box, looks like moon over mountains, rather than the conspicuous Attach option which requires everyone to open separately to see), how about the following way (shown below)?

1) With the Polar Grid Tool create a grid of the desired size (shown at 200 x 200 pt in red) with the desired number of dividers (7 both ways corresponding to the grid in your image), and position the grid to start at X = Y = 0;

2) With the Direct Selection Tool select the outer square and use Object>Path Offset Path with a negative offset to create an inner path behind the grid (shown in blue for an offset of -5 pt);

3) With the Direct Selection Tool select the outer square again and hold Ctrl/Cmd while pressing C then B then X then B to bring the copy behind everything else, then set the Stroke to None in the Tool panel; this bottommost path is invisible but crucial to the following:

4) Select everything, and Group (optionally), then turn it into a Pattern Swatch.

The above is shown in the top image.

5) Now you can draw a rectangle of any size and apply the swatch to fill it with (repetitions of) the basic grid.

This is shown in the bottom image.

As you can see, the offset paths in blue beneath the red paths correspond to the grey paths beneath the white paths in your image.

Click to get closer, Click again to get closer still