Thermal Depolymerization (detailed step by step instructions to make your own)
The process is really simple, it is similar to how alcohol is made. If you heat plastic waste in non oxygen environment, it will melt, but will not burn. After it has melted, it will start to boil and evaporate, you just need to put those vapors through a cooling pipe and when cooled the vapors will condense to a liquid and some of the vapors with shorter hydrocarbon lengths will remain as a gas. The exit of the cooling pipe is then going through a bubbler containing water to capture the last liquid forms of fuel and leave only gas that is then burned. If the cooling of the cooling tube is sufficient, there will be no fuel in the bubbler, but if not, the water will capture all the remaining fuel that will float above the water and can be poured off the water. On the bottom of the cooling tube is a steel reservoir that collects all the liquid and it has a release valve on the bottom so that the liquid fuel can be poured out. Here are some pictures to better understand the design:
And here is a video of a more expensive commercial Japanese version. This article says the small unit shown in the video isn’t available yet, only their larger industrial-scale units. The manufacturer’s website is in Japanese, so I emailed them to ask if they have price, specs and availability info in English. It looks like the small unit shown in the video will cost about $12K.