Trace and cut a ring out of the card paper (ours was sized to fit atop a gift box). Apply the first layer of buttons by pasting the card with glue and covering as much of the card as possible with buttons. Don’t worry about gaps, they’ll get covered in the next step.
Glue buttons, one at a time, overtop of the first layer, using the glue gun. Attach randomly and mix up sizes to cover any empty spaces. Once the wreath is almost finished, fill in gaps with smallest buttons and give the wreath a uniform shape.