Also, it would be funny if one day your looking at it then this is whats going to happen "Wow I'm so proud of myself for making this-BOOOOMMMM." It explodes so big that that file of Minecraft gets deleted and it says "Sorry, but that explosion was so epic you couldn't hold it, sorry for the inconvience."
I once made a huge Creeper head in an SMP server, the scale was something like 1 pixel to a 4x4x1 block, and I was going to fill it with chambers with one way doors. then the map got changed round. Bad times.