Vacuum forming Tommy Helmet

Andy taught us the prop making method of vacuum forming. To do this we are making WW1 Tommy helmets which we will paint to become one of our final props.


1. He made a paper template using the research he had gathered about Tommy helmets and some measurements from sizing it up to scale from a photo of a man wearing one.

2. Then he marked half the shape of the template onto a piece of plastic and then cut out the inner template piece of the plastic using a scalpel. He added an extra bit of lip to the edge to make it easier to use as a mould later on.

3. Next he attached this plastic to a long piece of wooden dowel by the centre line side using superglue.

4. After that he got a square of wood, measuring just bigger than twice the plastic stencil on either side. He had drilled a hole the size of the dowel into the centre block.

5. He then coated this in sealing agent to stop the wood taking in the water and cracking the mould. Andy also said to put Vaseline into the hole to make the dowel spin smoothly.

6. Once he had that ready he started to mix up a bowl of plaster by sprinkling plaster powder into a bowl of warm water until there was enough that they made small islands on the surface.

7. The mixture then got stirred until it had thickened as it started to set. This is where he told us we need to work quickly.

8. By adding mounds of plaster to the centre and rotating the plastic slowly around he built up many layers to create a plaster helmet mould.

9. Once it had set, we each cut a large square of thermoplastic sheeting and took this to John the workshop technician to use it in the vacuum former.

10. We placed the plaster mould onto the shelf, with a piece of mesh underneath to stop the mould getting stuck to the table, and lowered it pulling the side lever towards us.

11. Then we placed the plastic over the space above the now lowered mould, ensuring it was square and was leaving no gaps. This was then clamped down to keep it in place.

12. Next John had us turn on the heater and pull it over the top of the plastic to make it become more malleable to mould. We were told it was ready once the plastic had gone wavy and then looked smooth again.

13. Once it was ready we pushed back the heater and then using the table lever pushed up the mould into the soft plastic and pressed start to suck out the air and create the vacuum.

14. The plastic quickly formed round the helmet and we turned off the vacuum. It was then left to go hard. (If you couldn’t make a dent it was ready)

15. We unclamped and removed the mould and then used the ban saw and circular saw to cut off any of the waste plastic.

We now have our plastic helmet moulds.

I had to do this process twice as the first time the plastic did not mould tightly around the mould on one side. John said this was because we needed to leave the plastic warm for longer as the heaters had not fully heated up yet as I was the first of the group.