OU on the BBC: Lab Rats - Cast yourself

Production team

In the sperm programme, Mike and Zeron investigated their testicle sizes by making plaster casts. It seemed a shame to throw this valuable piece of research away, so...

How to make plaster casts of your testicles - or any other body part, come to think of it!

• Remove (shave) hair from the area to be moulded. If you don't, the hair will be removed for you when you pull the alginate mould off your body - and that option is a lot more painful!

• Apply lubricant (Vaseline is particularly recommended) liberally to the area to be moulded. This will allow the mould to pull away easier - but it won't stop hairs from being trapped, so make sure you've removed those hairs!

• Prepare alginate. Artist's alginate is available from all good art supply shops. To prepare the alginate you simply need to mix it with cold water according to the instructions on the packet. The finished consistency should be thick but able to be poured.

• To mould testicles, pour alginate into a polystyrene container which is deeper and broader than the area to be cast. Fill container to the brim. You can adapt this technique for other body parts.

• Put newspaper on the floor. When you press the container onto the testicles the alginate will overflow.

• Grip testicles tightly in one hand so that the scrotum is pulled against the testicles. This means your hand will also be included in the cast. With the other hand push the alginate-filled container firmly onto the testicles. If you aren't holding the testicles tightly they will pull away and flatten out upon contact with the alginate, creating a poor result.

• Hold the container in place until the alginate is set. The time will depend on the type of alginate used, but 5 - 10 minutes should be enough.

• Once set, pull the container slowly away from the testicles. You will now have a detailed imprint of your balls.

• To make the cast of this imprint, mix plaster with water. Mixing instructions should come with the plaster.

• Pour the plaster mix into the alginate mould (in the container).

• Tap the container all over in order to release the many air bubbles that could damage the appearance of the finished product - keep doing this for some time.

• Leave to set. This usually takes about 20 minutes, but check the instructions on the plaster packet.

• Once the plaster is set, break the container and pull the alginate away from the plaster.

• When all the alginate is removed you will have a detailed plaster cast of your testicles. What a handsome paperweight they make - enjoy!

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