You will need 10 buttons for the cuffs. Rowan used #G422724 in Silver from Groves and Banks in the UK.

Design is knit flat, then for finishing, the top and bottom edges are sewn together to form cuffs, and the garment is worn as a cocoon.

Finished measurements:
Total width: 54¼ (59 , 61)”/138 (150, 155) cm
Finished back center length: 27¾ (30, 31)”/70.5 (76, 78.5) cm