So, I'm currently working on building a CNC router and I like the idea of making it so that I can also use it as a laser cutter / engraver. I saw some jTech kits for lower wattage diode lasers. As I understand those would work fine for engraving non clear acrylic, and other materials, and some very light duty cutting.. but that is a little under powered for my taste, especially considering the cost of the kits. Thus I started reading about CO2 lasers. And while building my own CO2 laser from scratch does sound like a fun project, it's also a very tedious and hard to get right project from the looks of it. Looking on ebay, I found this: 40W USB CO2 Laser Engraving Cutting Carving Machine Engraver Cutter 350mm/s This looks very appealing. It is cheaper than many of the low powered diode lasers that jTech sales, and looks like it has the majority of the components I would need. So basically I'd be buying this just to strip out all the parts I want for the laser to retrofit onto my CNC when I finish it. The question I'm unsure about is just what would a 40w CO2 laser be capable of? As I understand, it should be able to cut clear acrylic, which is one thing I'd like to be able to do with clear plexiglass and such. Would this be powerful enough to cut very thin sheet metal? Something that you might would use for a metal face plate or something like that. Also on this unit, what is the point of the blue round thing? You can see it outside the box in one picture, and in another it's in the top back of the box and has the silver piece on the head depressing a section of it. This thing seems really cheap for what it supposedly is. Next step up for 50w CO2 I only see things costing 1300+ dollars. Also though, from all the DIY stuff I've looked at, they all have a way to add CO2 to it, these things don't seem to. Is it a sealed system already pressurized with CO2 or something? That could make removing the parts to place them onto my own CNC more difficult. But, if I did buy one of these, I'd probably initially just use it as is, but I'd eventually want to move the parts out to go beyond the 12" x 8" work space restriction.