Attached is a very simple macro that will:

1) start a sketch on the front plane

2) sketch a center rectangle and prompt for dimensions

3) create a midpoint coincident relationship between the base line and origin

4) prompt with the option to extrude the sketch.

It's a simple macro but as a beginner level macro user it took me way too many hours to find simple examples that allowed me to create it so I thought I'd share it a maybe save another new user some time.

prerequisites: part document open

the zip file also contains a bitmap for the toolbar.