Materials: mirror with frame, clear water proof silicon, caulk gun, and corks of course.
Put the mirror on a flat surface, if you are using a table you care about put something under it like old paper bags so that if a cork falls off while you are working you won’t end up with Silicon on your table like I did.
You don’t want to try to do too many corks at once take your time and let them dry! I did one row half way around and then took a break allowing the silicon time to dry.
The 2nd photo is of a clock I made a year or so ago for a fundraising auction.