I originally ran the engines on my Bobcat without a FOD screen, coz Uncle Bob said to do it that way.

A $400+ pebble convinced me otherwise.

Many of the commercial FOD screens didn't fit the Bobcat at the time, so I just went to my local hardware store and picked up a sink strainer, a big rubber grommet that will fit over the starter, and some thin rubber sheet. See e.g. http://www.rcuniverse.com/forum/m_35...tm.htm#3537832