There are two basic ways to save silicone. One is to brush on a layer of thickened silicone and then make a mother mold over that. (Amateurs usually use reinforced "plaster" some sort.)
The other is to pre-make a matching mother mold, which sits some distance from the surface you're casting, and pour liquid silicone in between.
A standard way to do that is to make a bazillion little balls of clay (some kind that doesn't inhibit the cure of the silicone you're using), and cover the object you're molding with them. Then mash and smooth them into a sheet. So if you want a fairly uniform 1/4" layer of silicone, put on a bunch of roughly 3/8" balls and then smooth them out.
(Another similar thing is to cover most of the object in strips of clay cut from a sheet extruded with a pasta machine, then cut wedges to fill in the gaps, then smooth it over.)
Once you've got the desired thickness of clay, cast your mother mold over it. (Be sure to "key" it---there should be protrusions and indentations here and there, so that the resulting silicone mold will fit exactly where it should in the mother mold, and only where it should. You don't want it slipping and scrunching.)
Once the mother mold has set, take it off and scrape the clay off it and the object. Put the object on some kind of spacer, sticking into the mother mold the right amount, and pour silicone in between.
Paul