Thoughts about why DM even purchased the incinerator:
In the TB trial it was suggested the incinerator was purchased for the purpose of disposing of the owner a vehicle they planned to steel, but for one reason and another the theft did not occur until several months later.
In this trial it is insinuated that it was purchased for the disposal of LB and the timing fits beautifully.
I think LB was the catalyst for acquiring the incinerator as he promised CN he would make her disappear. How do you make someone disappear - you kill them of course, but then how do you get rid of the body?
I believe DM having decided he needed the thrill of killing gave some thought as to what to do with the body afterward. Having decided burning was the most effective way to rid himself of the evidence and also being cheap he went the homemade route prior to purchasing the incinerator. I also believe he discussed this with MS and they thought they could make use of the incinerator in the commission of future crimes, which may be why DM decided to spend the money on a proper and efficient machine.
Just my ramblings. :thinking: