Note: The following text will always mention "playground", but the same steps can also be used to create a new contrib-project inside "contribs".
In the playgrounds-project, there exists a directory _template which can be used as a starting point. This template already contains the directory structure and svn meta data for a typical playground. Best is, to copy the template using svn commands. That is:
cd /path/to/workspace/playgrounds/svn copy _template nameOfNewPlaygroundnameOfNewPlayground/pom.xml, change the Artifact Id and the project name from "_template" to the name of the new playground.playgrounds/pom.xml_template directory in Eclipse or in the Explorer! In every case except "svn copy", the metadata will not be correctly updated, resulting in a corrupt svn checkout!