"scm" wrote in message
...
I have just 'converted' an old boiler flue into a cat tunnel by lowering
the hole a couple of bricks and lining the 'tunnel with ply. The Tunnel is
about 1 brick wide by 3 high
The Cat Flap is on the inside. The Cat manages to come through fine, but
boy does he complain that it is not as convenient as the old one in the
conservatory was!!
SCM

My friend has suggested using the extension tubes as well as a plywood
tunnel as well to be absolutely sure it wont leak.

Thanks for all advice, I think I will go ahead.