From t-squares and triangles, to ruling pens, masking tape, photo tape, rubber cement, spray glue, brushes, guache, drawing tables, technical pens, matte board, acetate, pica poles, french curves, proportional wheels, type spec books, etc.
What analog tools (not software or computer-based) should every designer have today and be comfortable using, and why?
Has software made all analog tools completely obsolete?
As someone working in printing, one of the biggest for me is the Pantone Color Book
Regardless of of how well your monitor is calibrated, it is crucial to know what your printed colors are going to look like. The discrepancies of the RGB values between Photoshop and Illustrator for Pantone Colors is bad enough as it is. I always check my formula guide before I commit to using a color in a design.