What material should I use for making prop weapons like a fake knife?

Article courtesy of Smooth-On, Inc.

Our materials are commonly used for making prop weapons. Our semi-rigid resins and rubber materials are very popular materials for 'stage-safe' weaponry.

Smooth-Cast™ 45D, for example, is a popular semi-rigid resin for this purpose. The Smooth-Cast Semi-Rigid line of low-cost semi-rigid urethane casting resins cure quickly to semi-rigid plastics that offer excellent impact resistance. These plastics are easy-to-use (mix ratio is 1A:1B by volume) and have a low mixed viscosity for minimal bubble entrapment. Vibrant colors are possible by adding SO-Strong™ color tints or Ignite™ color pigments. More info on Smooth-Cast 45D can be found by clicking here.


This FAQ article is offered as a guideline and offers possible solutions to problems encountered during mold making and casting. No warranty is implied and it is up to the end user to determine suitability for any specific application. Always refer to the provided Technical Bulletins (TB) & Safety Data Sheets (SDS) before using any material. A small scale test is suggested to determine suitability of any recommendation before trying on a larger scale for any application.