In my bathroom is a space about 12" deep and 11" wide that would be an ideal place for some shelves. Only problem making some is, the house is old and the walls on either side of this space are not quite parallel. They're about .5" further apart at the opening than at the back. Additionally, I'm not positive that either side meets the back at a right angle.
Does anyone have any suggestions for how I might make a template of such a difficult space in order to cut some shelves? Is there a tool I can use to measure the interior angles?