The acrylic 3D double liners are so final. During the development process, we have made it even more difficult to open the liner so that it cannot be unscrewed accidentally. However, we do not want to completely deprive the customer of the possibility to unscrew the product. (For example, we recommend that if there is still a small amount of colour left in the product, we add a little water to make the best use of this residual colour).