Silicone moulds are best stored clean and flat in a dust free environment, out of sunlight. They could be placed in dust proof bag or container. Most small moulds keep their shape in storage if not squashed or placed on top of other items. Some silicone mould manufacturers suggest pouring a plaster cast in the mould to keep its shape - some plaster dust may have to be removed before using again. Ideally not, as silicone can burn and moulds can warp when heat or a flame is applied. If you really have to, be very careful and use a small heatgun or an embossing heat tool that pushes out a narrow beam of heat, giving you better control of direction. It can still be very hot, so do not direct on the silicone and apply carefully.
How do I store my silicone moulds?
Can I apply a flame/heat to my silicone moulds?
Disclaimer: FAQ articles are offered as a guideline and possible solutions to problems encountered. It is up to the end user to determine the suitability for their specific task or application and no warranties or guarantees that it would work is implied. Refer to the TDS & SDS where available for manufacturer guidance. To determine the suitability of any recommendation or tip, a small scale test is suggested before applying on a larger scale.