It has been my observation that the bigger the ice cube the longer it will last. There is an upper limit of what will fit into the container, but regular ice cubes seem to be getting smaller, and the trays flimsier. After much observation and many trials, the Dannon Yogurt cups have the amazing property of popping the ice free even after many uses, and not getting damaged themselves, I also bought a lot of acrylic only to discover that some of it is extruded and useless for high detail. the cups themselves do not sit flat in the freezer and filling them one at a time iffy anyway.
So we have a use for the extruded Acrylic, the used yogurt containers, and I can get Ice “cubes” that fit my containers;
The design is easy enough but here it is anyway: