U-Boat Diorama

I was in my local model shop recently, and I found myself overcome by a mad impulse to buy a big naval kit.  They have a wide selection of large-scale WWII ships, mostly on the top shelves and covered in dust.  I spied a 1:72 Type IX kit for a bargain price, and quickly snapped it up.  But what then?  I already have a small-scale U-boat kit from last Christmas.  I decided to turn this one into