1. Create a canvas using "File > New". Assuming you use 50px squares, a 1000x1000-pixel image will create a 20x20 square grid. A 1200x1500-pixel image will create a 24x30 (flip-mat-size) grid. Setting the image to 160dpi should enable an output PDF of the (flip-mat) map to have a half-inch margin.

2. "View > Show Grid". This displays the default grid.

3. "Image > Configure Grid". Set the grid spacing to 50 pixels.

4. In the Layers Palette, choose "Patterns > Grid 50x50 blue". On your canvas, go to "Select > All" and then "Edit > Fill with Pattern". (Or "Filters > Render > Pattern > Grid" with Width 1, Spacing 50, Offset 0).

5. "Edit > Preferences". Go to "Tool Options" and raise the "Snap distance"; 25 will make the brush always snap to an intersection.

6. "View > Snap to Grid" should be checked.

7. In the Layers Palette, hit the "New Layer" button. Give the layer a name (such as Walls), and select Transparency as the Layer Fill Type. Make sure the new layer is selected.

8. Double-click the foreground color in the Toolbox Palette. Enter "18769d" in the "HTML notation" field.

9. In the Layers Palette, click on "Brushes" and select the "Circle (01) (3 x 3)" brush. A 9px brush creates a more visible internal wall.

Drawing and Coloring Walls

10. Draw some walls.

11. In the Toolbox Palette, choose the Fuzzy Select Tool, and make sure that "Sample merged" is off. On the canvas, click the area to be colored as impassable. Go to "Select > Grow..." and grow the selection by 2 pixels.

12. "Edit > Fill with FG Color". Repeat 11 and 12 to color in all the walls.

Placing Doors and Other Elements

13. "File > Open" and choose "door.png". "Select > All". "Edit > Copy". Close "door.png" without saving.

14. On the canvas, choose "Edit > Paste". In the Toolbox Palette, click the Rectangle Select Tool. Move the door and anchor it.