You make it sound like you need something to type on when talking between co-workers. What's wrong with using a computer? Simply open up a new MS Word document with the font settings at size 20 and type away.
One of my advisors did that for me and other deaf people under him. He created a MS Word template pre-set with an easy-reading font at size 20. That shortcut sits on his desktop. Whenever a deaf student comes in to see him on a short notice, he simply double-clicks on that shortcut and types away. He even offers to save the document to send to that student via email and/or to print it out as well.
