Once I started to source raw materials I found that I needed to tweak a few of the dimensions to fit what was practical within both my budget and my ability. The ribbed portion of the original guns seems to have been turned from a solid piece of perspex (or at least a very thick walled perspex tube) and that type of stock is prohibitively expensive. I decided instead to make it using a series of stacked discs and rings cut from perspex sheet. I found that very thin-walled perspex rings tended to distort and so had to modify my dimensions to allow for that, while preserving the proportions. The outer curves were turned and polished by hand on my lathe. Diffraction in the clear curved forms tends to magnify and distort even slight imperfections making it very difficult to get as clean a look as I'd have liked. I also discovered that perspex cement will bond plastic to wood, meaning that the wooden former I used to align the rings had to be cut free and the inside re-polished, resulting in more blemishes. With hindsight, I should have sealed and waxed the former and probably used mould release to be safe.

The central barrel was turned from a piece of perspex rod. I formed the dome near the end with a combination of a radius cutter and hand turning by eye. I drilled a hole in the base for the lighting. At this point I discovered that it is possible accidentally to weld a drill into perspex if your cutting speed is too fast, making it nearly impossible to extract it. Luckily I was able to heat the protruding end of the drill with a blow torch just enough to soften the plastic and work it loose without damaging the barrel.

The grip came from an old power tool. It had originally been held in place using a long bolt but since I needed to be able to pass wiring through it, I replaced that with aluminium tubing that I threaded at both ends. I widened the hole through the grip to allow for the thicker tube, while being careful not to damage the hexagonal hole that would hold the nut. I also bored a wider hole in the base of the grip to accept the connector for the curly cable. I then needed to polish out thirty years' worth of wear and tear to try and make the grip look clean and new.

The grip tube was secured to the body of the gun using a simple aluminium bracket. I also made an aluminium collar with a dished face to couple it onto the domed body.

I used a plastic hemisphere for the base of the gun and cut the body from plastic tubing, heat-forming the thumb guard and lower plate.

The trigger button came from a doorbell. The original prop would have contained an incandescent bulb but I decided to use LEDs. To try and maintain the feel of the original lighting, I chose warm white LEDs and built a simple fading circuit so that they would dim gently when the trigger was released, as if cooling down. It's quite a subtle effect but I'm pleased with it. I considered using small batteries in the body of the gun but it seemed silly when the cable and belt box would be needed anyway to complete the look of the replica. I used miniature inline connectors in the cables to the trigger and the grip so that if worst comes to worst it can be dismantled for repairs without de-soldering. This also made final assembly easier as all the soldering was already complete.

I primed and sprayed the body parts in gloss black acrylic. Despite all the careful preparation, final assembly was still tricky and a little stressful. Order of assembly was critical (an import factor when designing blueprints; it's all too easy to design something that is ultimately un-buildable due to a fixing bolt being inaccessible). The electronics were checked repeatedly throughout construction. Extreme care was taken when tightening screws as a slipped screwdriver could easily gouge the paintwork. I was pleased with how securely the push-fitting parts locked together but to be extra safe I used PTFE tape in some of the joints.

The holster for the battery pack was hand-stitched from leather. It was a fiddly job as there is very little room to maneuver inside once the sides start to come together. I went through quite a few needles and some bad language. Once assembled and formed, it was dyed and given a finishing coat. The colour isn't exactly right but does have a 'hardware' look that I quite like.

While this project was more about detective work and fabrication than creativity, it was very satisfying watching such a familiar object take shape. The gun was on display at a signing by Paul Darrow and the ultimate thrill was seeing it handled by him. He was also kind enough to sign it for me.