Grease two large baking trays with the oil. Crush the fruit-flavoured sweets by colour and put into separate bowls. Arrange small clumps of coloured sweets onto the trays.
Put the mints in a saucepan over a medium heat. Cook gently until melted, stirring occasionally with a metal spoon. Once melted completely, remove from the heat immediately, otherwise the mixture will burn and discolour.
Working quickly, design your charm shapes (making sure they have a hole for threading the ribbon) by drizzling spoonfuls of the melted mints over the clumps of coloured sweets on the trays – they will melt into your shape and add interest to your design.
If the mixture hardens while you are working, return it to a low heat to soften, but try to make as many as you can in one go – the more you heat the mixture, the less clear the final charms will be. Leave to set for about 10 mins until hard and cool enough to handle, then remove from the tray by hand – be careful as they will be quite brittle. Tie a length of ribbon through each charm for hanging on the tree. Pack in a box between sheets of baking parchment so they don’t stick together. Eat within 3-4 days, or keep as a decoration for up to 4 weeks.