Crochet Granny Tissue Box Cover

A 4,5mm hook

USA crochet terminology:
ch - chain
dc - double crochet
st - stitch, stitches
sl st - slip stitch
sc - single crochet

Working ch 2 instead of first dc of the beginning of each following round.
Rnd 2: *(3 dc, ch 2, 3 dc) in the next stitch - we got a corner cluster, skip 2 st, (3 dc, ch 2, 3 dc) in next st - we got next corner cluster, skip 2 st, 3 dc in next st, skip 2 stitches. Repeat from * one more time, join with a sl st.
Rnd 3: sl st across the next 2 st, sl st in the corner ch-2-space, *(3 dc, ch 2 , 3 dc) in the same ch-2-space, 3 dc in the space between the next two 3-dc-clusters, (3 dc, ch 2, 3 dc) in the corner ch-2-space, (3 dc in the space between the next two 3-dc-clusters) two times. Repeat from * one more time, join with a sl st.
Rnd 4: sl st across the next 2 st, sl st in the corner ch-2-space, *(3 dc, ch 2, 3 dc) in the same ch-2-space, (3 dc in the space between the next two 3-dc-clusters) two times, (3 dc, ch 2, 3 dc) in the corner ch-2-space, (3 dc in the space between the next two 3-dc-clusters) three times. Repeat from * one more time, join with a sl st. We have a rectangle shaped top of our cover.
Follow without a making corner clusters.
Rnd 5: sl st across the next 2 st, sl st and 3 dc in the following space; follow making 3-dc-clusters between the 3-dc-clusters.
Rnd 6 - 16: follow Rnd 5.

Rnd 17: sc in each st around, join and fasten off. That's it!