This model requires 3/8in width dowel's to be built. In USA you can find this at you local hardware store for about a dollar (Link). You can calculate how many dowels you need based on the width of the bowl. For the one in the pictures, you need 3 (200mm * 16) since each dowel rod is 48in or 121cm. Just print the base without supports (if your printer can handle it) and cut 16 equally sized dowels. Attach them to the base and viola.