Test Cases for Pen

These are the possible test cases for Testing of a Writing Pen

T.C. 1:  Verify whether the cap is opening or not
T.C. 2:  Verify whether there is a riffle in it or not
T.C. 3:  Verify whether it is writing or not
T.C. 4:  Verify to write on different objects
T.C. 5:  verify is there any leakage during writing
T.C. 6:  Verify the characters are visible
T.C. 7:  Verify whether it is refillable or not.
T.C. 8:  verify is there any damage.  
T.C. 9:  Verify if it is breakable or not
T.C. 10:  Verify it is comfortable or not
T.C. 11:  Compare it with other models

If you can add some more test cases in it, plz add, its a practice exercise for you.