To make the mini eco-resin hearts you will need a silicone mould available from Amazon and other shops. The mould is for making chocolates and cake toppers, so available in lots of places.
You can add metallic flakes/sheet to the mould indents if you want to add some shine.
Mix 10g of A1 eco-resin liquid, colour with pigment, and then mix in 20g of A1 powder. Stir for at least 1 minute to make sure it's a smooth consistency.