Ok I've stuffed the iron with Aluminium foil and inserted the heater. Time and testing will tell if the foil is packed in around the heater tight enough.
The label on top of the temperature controller is just my reminder of the wiring diagram.
I'll start on a box to hold it all tomorrow. I'm also waiting on a digital temperature probe which will be inserted in the end for repeatable temperatures.
I found some cheap digital controllers which will set and hold a temperature for a set time on ebay and might look into fitting one of these but this iron was only supposed to be a stop gap measure until I could afford a silicone heating blanket, so we'll wait and see. Wiring it up could be a nightmare as these things can be wired a number of different ways.