We recently updated our silicone mold casting frame design. The casting frames are now slightly shorter than the mold. We use seconds for our testing and samples, many of which were slightly shorter than our molds. Those shorter frames became the preferred frames as I was using the molds.
When I would over pour, I like to use a popsicle stick to level or remove extra medium. When the frame was the same height, I was unable to get it close to the edge. This resulted in messier castings and casting frames.
I hope you like the new design as much as I do!