16 inch speaker seal mold.

thingiverse

This is still a work in progress. Initially, I assumed the use of wash-and-go avail mold generators, but it appears that it's a bit more challenging than expected. To use just manually created negative mold, you'll need to fill it with silicone (or a silicone-latex mix if you intend to glue it to a speaker later). Then, insert a few spacers on the edge, such as pieces of 1mm wire. After that, press the 'seal' model against it. In theory, this should cause any excess silicone to seep out. However, for molds of this type, I believe this will be sufficient to use them effectively. To finalize the process, simply trim after curing and repair your speaker as needed.