Depending on how your mold was made, you can sometimes take a solid mold with a part buried inside. Carefully cut into the center of each side in a zig zag pattern, spreading the mold open as you cut. Cut until you reach the part and if necessary, cut any "strands" of silicone going through the part. After your able to pop your master part back out, the mold should go back together in a locking fashion if your cuts were done correctly. I used to make single truck wheel molds all the time by mounting the wheel on a pedestal that ended up being the pour spout. Mix the silicone and completely cover the part. Afterwords, I would cut them apart as mentioned above. These molds produced flawless pieces with no flash for up to 50 castings. I was using Shin Etsu clear silicone though. After the silicone cured it was crystal clear. You could easily see the part and know where to cut too. I have done it with the GI1000 blue silicone as well though.
Edited by Ben, 27 September 2012 - 05:55 PM.