I made this mini tray using bulky weight cotton yarn.
It can be used as coaster or accessory tray.

for larger size,
round1:6sc, round2:12sc, round3:18sc, round4:24sc, round5:30sc, round6:36sc, round7:42sc, round8:48sc, round9:54sc, round10:60sc
on round11, make popcorn stitch as same as smaller one.

size:
smaller one is 11cm in diameter and larger one is 16cm in diameter.

download this patten:
japanese http://atelier-mati.com/?p=5954
english http://english.atelier-mati.com/?p=194