This might be a bit overkill but it's kind cool if you also need a mini multi-tool. I don't own this but it has great reviews.

https://www.amazon.com/gp/aw/d/B06X3QP4VY/ref=mp_s_a_1_4?ie=UTF8&qid=1517258684&sr=8-4&pi=AC_SX236_SY340_QL65&keywords=ink+pen+light&dpPl=1&dpID=516Ev2WACCL&ref=plSrch