I don't think I knew about the HRP movie, though I remember seeing the TV show. Mama Cass? Wow! And Witchypoo's house is great - it'd be great as a garden shed.
My megalomaniacal idea was to make a matchbox that was embedded in a tree, as if the tree had grown around it. I was going to find a dead tree with a suitable knothole, cut out a manageable section, carefully split it in two, make an opening for the box and glue the halves back together again so Cackle would have to use an axe to get the matchbox out. But I've moved on to less weighty plans.
Too close to my idea for comfort
Er, even though my thoughts were going in a similar matchbox-in-tree direction I've hit the brakes now. Good thing I received something in the mail today that sparked another idea.