Dermot,
I'm taking about something simpler than the shapes Wouter and John have drawn.
A "Super Simple" 12 ft cat could be drawn up with building instructions in a couple of days and a couple of weekends to build plus painting if thought out carefully.
So I suppose you're right, it could be done by the time the grand kids come along.

I know that the voices in my head aint real,
but they have some pretty good ideas.
There is no such thing as a quick fix and I've never had free lunch!