Are the shapes such that you could use specially bent pieces of metal to screw into the vent and then flap over the vent top and metal screw into the vent covers? Micromark's website has metal bending pliers. Sukie (not a vet) Recommended ferret health links: http://pets.groups.yahoo.com/group/ferrethealth/ http://ferrethealth.org/archive/ http://www.miamiferret.org/ http://www.ferrethealth.msu.edu/ http://www.ferretcongress.org/ http://www.trifl.org/index.shtml http://homepage.mac.com/sukie/sukiesferretlinks.html all ferret topics: http://listserv.ferretmailinglist.org/archives/ferret-search.html "All hail the procrastinators for they shall rule the world tomorrow." (2010, Steve Crandall) On change for its own sake: "You can go really fast if you just jump off the cliff." (2010, Steve Crandall) [Posted in FML 7325]