This is a mold for my Two Pearls Plug.
Print two of those. Sand mold surfaces!
Use M5 60mm screws and nuts for clamping mold parts together. They held to keep everything aligned and closed.
Mold outerdimensions: 11cm x 6cm x 3cm
Pearls about 28mm in diameter
Volume: 44.7cm3 – You need 45ml of water for an ice toy.