One of them being that you should always pour your silicone from one place and let it coat the piece being copied. Otherwise, there might be lines on the mold. Another tip is for DIY mold release ...

As a bonus, molds treated with an acrylic dip do not need a release agent: silicone simply refuses to stick. As usual, [Jan] provides plenty of photos and details of what did and didn’t work as ...

SSP2575 "has a history of use in space programs and is available as a ready-to-mold compound, compression-molded sheet ... "In the near-perfect vacuum of space, most silicone elastomers release gases, ...