
The infamous homemade beltfed shotgun:
http://tslrf.blogspot.com/2009/11/home-made-belt-fed-shotgun.html
or the equally infamous homemade flamethrower:
http://video.google.com/videoplay?docid=-3749273208960452991&ei=jcJVS5r8Dpm-qQLL15iRBA&q=homemade+flamethrower&hl=en#
IIRC, that particular model had the nasty habit of “banana peeling” at the most inopportune moment.