For fitters and pipe welders, there's the black book. It is small, but mighty for fabrication.
And it literally fits in your pocket! This one is really good too : Handyman In-Your-Pocket https://www.amazon.com/dp/1885071299/ref=cm_sw_r_cp_api_glt_fabc_PXTPY4HJ0VC93Z4NJQ2Y?_encoding=UTF8&psc=1
https://www.amazon.com/dp/B00IG46NL2/ref=cm_sw_r_cp_apa_fabc_TX6HHE3YY7KN2JY3JYR5
6" digital mitutoyu. Digitals are nice. Quick and easy to read, concerts inch to metric with push of a button. Water resistant. Get a 6" unless you believe that you need an 8". Mitutoyu makes a nice caliper.