When drawing shapes, there are several ways to add outlines. PowerPoint 2007 and newer versions offer great variations that you can play around with. For instance, you can add solid or gradient line color to the shape itself. You can also add transparency to the outline depending on your preferences. More advanced features would be the Line Style which includes setting compound type, dash type, width and etc. In this article, we would explore even further, that is, creating your own Brush stroke or calligraphy styled outline in PowerPoint.
The brush stroke outline however, is not something that is available natively in PowerPoint. Therefore, we would need to create it manually. To do so, you will need to make use of Curve lines. First, draw a simple shape to start off with (e.g. Square, triangle etc). Next, click on Insert > Shapes > Curve (under Line section). Carefully trace the outline of the shape. Start off with the shape edge first. Add a point on the first sharp edge by left clicking on it. Then, at every straight or curve segment, add a point with a bump (slightly away from the shape), thus making it looks a little thicker than normal outline. The bump does not necessary has to be in the center, depending on how you want the brush stroke outline to look like. At the next sharp edge and onwards, hold down Ctrl key and add the point. This prevents forming a curve edge which would not be what we are trying to achieve. Continue tracing the shape till you meet the last (also your first) sharp edge. Hold down Ctrl key again and double click on the sharp edge to end the whole process. The brush stroke technique requires some practice to make the outline looks natural. With practice, you can then move on to complex shapes such as those with many curve and straight segments. For some examples on brush stroke outline, take a look at the PPT file attached.