Toothpicks work fine. Even old paper or wooden matches can do the job.
If you are worried about the fumes from Silicon....don't use it! To seal it 'dry', you might be able to make a gasket out of an old bicycle inner tube or even go to one of the home stores for sticky backed foam....1/2" wide should do.
If you are worried about the fumes from Silicon....don't use it! To seal it 'dry', you might be able to make a gasket out of an old bicycle inner tube or even go to one of the home stores for sticky backed foam....1/2" wide should do.