Comment by cweagans

CNC sounds like kind of a bad fit unless you're going to mill the entire frame out of a solid piece of wood -- you'd lose a lot of material to the router bit and still have to do a fair amount of finishing by hand. For mitered joints like this, there are computerized saws that can feed and cut the lumber pretty precisely, but those are very expensive.

I'm not super clear on whether or not you're doing all of this by hand or working through a factory. If it's the latter, I would recommend just setting your expectations for the final product very clearly and then make sure that the end product is meeting those expectations. If you're doing it by hand, practice makes perfect! Go to your local lumber yard store and get some construction grade pine or fir boards and cut several dozen miters by hand (you can also invest in a compound miter saw -- that's generally useful for any woodworking that you'd want to do down the road as well and you can find them used for ~dozens of dollars or brand new for ~100-500 depending on features, size, power, etc -- just make sure you've got a good, sharp blade with lots of teeth for a nice smooth cut). You'll get the hang of it. For soft woods, clamping pressure and even glue distribution matters too -- you can clamp them a little tighter and the wood fibers at the boundaries between the boards will crush down a bit and help to even out the joint. That doesn't work so well with hardwoods though - you'll have to be pretty precise to get those done right.

Depending on the thickness of your wood, you might be able to do something with a laser cutter, but you'll need to figure out how to square up the edges appropriately (since laser cut edges on thicker lumber are rarely perfectly square).

If you're particularly lucky, you might be able to find somewhere that will give you some time on a water jet. Those edges will be perfectly square and everything will be cut perfectly -- just make sure to thoroughly dry your parts before assembly.