There are three common reasons why parts are incomplete:

1. Not enough material was prepared

Recalculate the amount required and try again

2. The material had started to cure before the mould was filled

Pour the material as soon as it is fully mixed

Choose a material with a longer pot life

3. Air was trapped in the tool

When a silicone mould is made, thin wires are generally cast into it to vent the air from the tool to use as the material is poured in.

To add extra vents after the tool is made insert thin tubes, such as hypodermic needles.