Tim Smalley has a cool one.
It is the first thing you see when you click on the link for what's on the bench in the general forum .
He was kind enough to share the plans with me. It is a "back burner project for me,but not far from complete. The principle is sound and can be easily modified.
If it is not what you are looking for,it is a great starter to try the principles.
SubCommittee Vice President 2006-2008
Author-Russian Submarines, Guardians of the Motherland
Member-Saint Petersburg Russia Submarine Club