Newbie looking at 6040 (China CNC) for polypropylene 15mm sheet

[Zeeflyboy]

Well it's certainly a lot more viable for low scale production than 3D printing is... It all comes down to how much volume you are expecting.

Injection tooling is indeed pretty expensive, only really makes sense if you are selling relatively high volumes and can spread the cost against at least several thousand units. I didn't pay for it myself but when we had the tooling made up for a drone I designed I think it was in the order of $10,000 to get the molds made (in china).

You would probably find a CNC a useful addition even just from a prototyping stand point - 3D printers are great, but the ability to work with PCBs, a variety of plastics, composites and some metals opens up more options to you that might be useful... not to mention much faster for making most things.

6040 is very much a generic term - some manufacturers are better than others, especially on the electronics front... One advantage of just buying a frame and adding your own electronics is that you can buy some better kit which you can then transfer to another machine if you decide you need something bigger or better.

I would recommend that you go for one with proper profile rails (e.g. HG20) rather than round rail - they are far superior. That particular machine you linked to actually simply has completely unsupported round rail for the X-axis gantry - don't bother with that... I had a similar machine in the past and there is a significant amount of flex from that design even when just pushing the spindle with your hand.