I need to create photo frames that have 3 corners square and 1 corner
rounded. If I use Object > Corner Effects, it affects all 4 corners.
Is there any way to do this, other than drawing the boxes with the pen
tool?

Also, is there any way to apply different stroke weights to different
sides of a frame? For example, suppose I want a 1 point stroke around a
box, but the left edge to have a 5 point stroke.

James