Whilst I am waiting for some parts to arrive for my RepRap, I found myself with an hour spare and decided to try making a vac forming machine.
It has a small footprint and is made from 12mm MDF. The clamping frame to hold the plastic sheet is 6mm MDF held together with 8xM4 bolts.
I haven't had chance to try it yet as I don't have any plastic sheet. We used to have a vac form department at work years ago but they outsourced it, so no free test sheets from there.
I intend to use it to make the domes for the Milestag sensors from acrylic sheet used on greenhouses.
Here are some pics:
Here is a side on view showing the clamping plate: