Question

Where do you keep your certificate?

I taped a standard mailing envelope (minus covering flap) inside the
cover of my logbook. I keep my medical, certificate, and CFI's
business card in there.

Said logbook is usually kept in a drawer at home, since it's been over
a year since I've flown as PIC. Since then, I've usually gone up with
my dad, who has an ATP.

However, when I was acting as PIC (and when I will be again this
summer, after I get my tailwheel signoff) the logbook went into my
flightbag with the sectional and E6B.