Introduction: Plastic Moulded Lens Covers Instead of Vacumn Forming
I'd nearly finished building this Bladerunner baseline detector prop, but it called for lens covers on it. As I've not yet got a vacumn former I decided to try and make some moulds and form something myself out of clear 0.5mm PETG
Step 1: 3D Model of Buck and Mould
First up was to take the STL models supplied and load them into Tinker cad. The basic steps were to use the lens as a negative and use it to carve a bowl shape. Then I duplicated it and shrunk it by 1mm on the X & Y and 0.5 mm vertically. This I then added to a little plinth and loaded them up into Slic3r and printed them out at around 40% infill. Once printed a little light sanding was done to clean them up. Once that was done I just fixed one part to some wood ready for the moulding.
Step 2: Heating and Moulding the Plastic Sheet
Next step was to take a small square of clear 0.5mm PETG and heat it up with a heat gun until it goes floppy. Use a pair grips to hold it so that you dont get burnt , although its not too tricky. Once it was floppy then lay it over the mould and press the other half on top squeezing it together. It pretty much cools instantly.
Step 3: Mould Release
Just pop the mould apart and now you have a nice moulded bubble. Although it has a fair bit of excess plastic on it. That can easily be removed. The trick to getting it very clear I think is keeping the temperature just enough to melt but not too high to cook it. A bit difficult with a heat gun, but for this purpose it was fine. I think if you were going to want a good transparency then you might just heat the plastic up in an oven at around 150 degrees Centigrade, but thats for another time.
Step 4: Finishing the Lens
The plastic easily comes off and then you'll need to trim the excess. I just a sharp scalpel to trim it as close as possible. Finishing the edge can be done with grit paper,small files and you end up with a nice lens cover. This popped straight into the holder and when placed into the baseline detector it really sets it off. Its amazing how the addition of some curved lens really sell the prop as looking much more real.