Sometimes it is pretty cool to see total sq of a group of objects, total # of porches, or group together roof planes, or do something with a group.   Since not everyone is a software developer, have time to research Ruby... Here is a simple way to do this: We want to use array of arrays [or to be exact hashmap of hashmaps] to store the data that will be displayed later. I use a single global: $tree. The hashmap $tree["rooms"] will be storing rooms and whatever properties you