I bought the kits to speed up the build, and I recommend them. Quality parts (some are on the cheap side  but still good quality). You can see my finished box in the picture.

Just a few comments and questions @rawcnc:

1. The lid has several smole holes as addition to the fan hole. Why?

2. I am going to glue aluminium screens over all holes to prevent dust build-up.

3. I labelled all connectors, cables and parts. I recommend that to everyone.

4. I miss a document noting all steps with timing references to the video. It would make things easier.

5. Since several metal parts (corner aluminium profiles) are exposed, I added ground connectors to them. It is not strictly necessary, but adds extra safety. The unit runs on mains voltage after all.

6. When the estop breaker is mounted the correct way (countersunk side facing in), the holes for the angle brackets for the PSU come to close to the side panel and cannot be mounted.

6. The supplied cables have colors yellow/green, reddish brown, blue and black. Usage for yellow/green for anything but ground is usually not allowed/recommended but since this is a diy project it is not a problem. However, it's worth noting that if you in the future need to open the box and replace or add something  this may become a risk for short-circuiting something.

7. In the machines you sell ready-made, there are handles mounted. Since that box has aluminium profiles that run alongside the longer sides, those handles cannot be mounted the same way on this box. But I would still like handles like those on mine to make handling easier.