This plugin, which gives a polygon_selection thickness, is made by IMAIZUMI, Yoshiaki. firstname.lastname@example.org
How to use.
1. Select polygons.
2. Select MakeThicker from "Plugins" menu.
3. Set Maximum Angle, Offset-value and Preserve_groups_option to extrude, and click "Apply".
4. The makeThicker-plugin uses the smooth-shift tool instead of the extrude-tool if the check-box for "smooth-shift" is checked.
Offical site is down almost 2 years but this plugin working R9 R10 R11 R11.5 and R12.