Step 1: Mold actuator body

Elastosil needs to be mixed in a 1:9 ratio of Part A:Part B, by weight. The total amount you need depends on your mold. Here, we will make 50g total of Elastosil, so we need 5g of Part A.

(If using a different material see the vendor instructions on mixing ratios)

Take the bottle of Elastosil Part A (red fluid) and shake it vigorously, as it tends to settle. Measure out 5g in the cup, making sure to pour slowly so you don’t overshoot. If you do overshoot, you can pour some back into the bottle, or add more part B later to compensate and maintain the 1:9 ratio. [Video]

Now add 45 g (5g x 9) Elastosil Part B (white). Being accurate within 2-3 grams is okay. If you pour too much, you can remove some material with a spatula. [Video]

Pour a layer of the mixed Elastosil into the main body of the mold, going slowly to avoid spillage and trapped air pockets. Do not pour right to the open end of the mold (where the cap will go); stop about a centimeter from the edge.

When you have finished pouring, take the rod and come in at an angle to insert it into the hole at the base of the main mold.

Once the end is in the hole, slowly lower the rest of the rod into the elastomer, then slide the end cap forward to match the mold.

Make sure to push the rod really hard into the hole because the elastomer in there will resist the rod from going in and locking properly.

Now pour another layer of Elastosil to cover the rod.

Allow the Elastosil to settle for a few seconds and pop any visible bubbles.

Attach clamps to hold the mold together. Attach the first clamp at the bottom of the mold.

Attach another clamp near to the top of the mold, and on the opposite side so that the mold can balance while standing upright.

Clean any spillage using paper towels. The cap will probably have popped up when the clamps were attached. Push it back down until it snaps into the hole.