The trap door is made in three parts. The door, chamber curve and the solenoid bracket.

1. The Door

The door can be built by using these dimensions and carefully cutting a single piece of 2.5mm thick Styrene sheet 109mm long and 82mm wide. Mark a line 55mm in from the 82mm edge as this will be the crease line you will use to bend the styrene to a 55 degree angle. Styrene can be bent easily when it is gently heated over a gas flame and bent over a wooden straight edge.

Note: Adult assistance is required for this step. Ensure adequate safety measures and gloves are used during this process. The gas flame should never directly touch the styrene as it could burn, ignite or discolour. This must be done outdoors with adequate ventilation and a fire safe environment.

In order to get a good clean bend I recommend making up a thick wooden block template which can be cut to the correct angle. This way, when the styrene is heated until malleable, it can be quickly draped over the wood and pressed into shape with another block of wood.

Once the correct angle is achieved cut a solid metal rod of (2mm diameter) long enough to overhang each side of the Trap Door by 7mm. Glue the rod into the crease of the Trap Door with a strong two part epoxy glue.

2. The Chamber Curve

The Chamber Curve is made from very thin Styrene (0.5mm) which is bent around two supporting styrene struts as seen in the photos. Styrene glue (Model Plastic Glue) is used to hold the Chamber Curve, Struts and Door in place.

Note: When using Styrene glue ensure you work in a ventilated area and follow the safety instructions.

3. The Solenoid Bracket

The picture and diagram shows a special aluminium bracket has been made and attached to the centre of the underside of the Trap Door. This is used to attach the Solenoid coupling rod that you will build later.

The picture also shows another adjustable aluminium tag that can be added later if the door does not stop in the correct position flush with the surface of the plastic case.