So I've gone back to the beginning and remade it. Most of the corrections made to the previous test build's parts turned out successful, so the construction process is smoother. It's still quite intensive, though. Here are some of the changes:
1. All the parts have a texture now, like on the V1. I'll provide several versions of the wooden textures, so people can select based on preference and printer capabilities. Mine prints everything lighter than normal, so the regular dark brown texture came out somewhat orange, but it's still preferable to the previous test build's flat red.
2. The internal guide rails and magazine catch have been redone, and the magazine can be inserted and removed correctly. The shape of the housing isn't entirely realistic, as there are no rivets attaching it to the bottom of the receiver, but at this point It's better to avoid taking steps back in the process.
3. The grip has some gaps resolved. Its final, well-fitted version is visible at the bottom.
4. The trigger, disconnector, and hammer have been improved so they don't require quite as much hand work to get right.
5. The gas tube lock is now a straight pin that can be inserted and removed, because the original, realistic, shape was too prone to deformation.
6. Auto sear has been removed, because the receiver walls are too thick to give it any room to move. It just kind of sticks back at an incorrect angle, so the auto pin will be just bare.
7. There is now a serial number on the bolt carrier, front trunnion, and dust cover.
8.There will not be a center support rivet, simply because it might obstruct things and wouldn't offer a real benefit.
9. The dust cover is strange, because its exact shape depends largely on the way it's put together. I've made a lot of tweaks to it and built several of them, but it still has to be slightly shaped and fine tuned by hand to get a proper fit. It's not as obnoxious as the V1 dust cover, because its sides are straighter, and there aren't so many nooks and crannies. However, this also means the sides are thinner, which introduces its own difficulties. The trick to building it is to use binder clips. Find a bunch of binder clips of various strengths and sizes, and use them throughout the construction to hold various parts of the dust cover together. It saves a lot of trouble.
I'm tempted to make a simplified version, because many of the details in here are more trouble than they're worth.