Gather all the broken pieces of coffee cup.
Place the round bottom of the cup into the sand and be sure the part that needs to be repaired is pointing up. Sitting the cup in the sand will help secure the cup while you work.
Brush all ceramic dust or debris from around the broken edges on the cup.
Squeeze out a small amount of epoxy and mix with a small amount of hardener. Each portion should be around the size of a dime.
Take your toothpick and apply the mixture of epoxy and hardener around the edges of the broken part of the cup.
Press the broken piece back in place and hold for 60 seconds. You need to be sure the glue is set before you let go.
Remove the cup from the sand after the epoxy has set completely. You can then wash the cup as you normally would.