Article in English: You can find these in stores specializing in casting and mold-making supplies. You can also sometimes find these in a well-stocked arts and crafts store. Most kits will contain two containers labeled "Part A" and "Part B." Sometimes, you have to purchase them separately. Do not mix the silicone yet. Find a cheap, plastic food container made from thin plastic. Use a craft blade to cut out the bottom. Don't worry about how neat or jagged it is; this will eventually be the top of your mold. Choose a container that is a little larger than the object you want to make a mold of. Remove the lid from the container. Cut several long strips of packaging tape, and lay them across the top. Overlap strip by about ¼ inch (0.64 centimeters). Leave a couple inches/centimeters of tape hanging over all sides of the container.  Run your finger along the rim to create a tight seal. Make sure that there are no gaps, or the silicone will pour out. Once you fill the container with silicone, there is a small chance that some may leak out from under the tape. This will kept prevent the silicone from leaking out all the way and ruining your work surface. Place the container onto a flat, stable surface with the cut/open side facing up. Place your items into the box, and press them against the tape. Do not let the items touch the side of the container or each other. Also, make sure that the design portion of your item is facing up, and the back is pressed against the tape.  Flat-backed items work the best for this. Wipe the items clean beforehand, if necessary. You will always have mix Part A and Part B together. Some types of silicone are supposed to be measured by volume, while others need to be measured by weight. Read the instructions that came with your silicone closely, then measure them accordingly.  Pour the silicone into the cup included with your kit. If your kit did not come with a cup, pour the silicone into a plastic, disposable cup. You need enough silicone to cover your items by ¼ inch (0.64 centimeters). You can do this...

Summary in Indonesian:
Beli paket peralatan untuk membuat cetakan silikon dari toko. Potong bagian bawah wadah makanan plastik. Rekatkan potongan lakban secara tumpang tindih di bagian atas wadah. Lipat ujung-ujung lakban ke sisi wadah. Masukkan benda yang ingin dicetak ke dalam wadah. Ukur banyaknya silikon yang dibutuhkan berdasarkan instruksi yang tertera pada kemasan. Aduk kedua bagian silikon sampai warnanya merata. Tuang silikon ke dalam wadah. Biarkan silikon sampai solid. Buka cetakan silikon. Keluarkan benda dari dalam cetakan. Gunakan cetakan.