Mechanical gear shapes can be created easily in Inkscape. This tutorial will show you how, and give you an idea on applying filters to make the finished design look old and worn.
Link to Inkscape Filter Guide: http://www.littlewebhut.com/inkscape/graphics_filter_guide/
Combine elipses to create the outline of a bowling pin, then use gradients to create the shadowing effect for that new object.
A good explanation on snapping(connecting) nodes is also introduced in this tutorial.
