Your camera is in that flying admin mode.
Oh I didn't notice that.
That means I have to:
- Manually take a screenshot while the texture quality depends on your GPU 3D settings
- Crop the image to the correct size and that requires resizing the image so the brick fits the image pixel perfect. This could reduce the texture quality depending on how you do it. I'd argue you will never get perfect results if you resize the image. Of course you could spend several minutes aligning your camera so the brick is already at the correct size when you take the screenshot.
- Save the screenshot in an image editor for each brick.
- You need the actual brick to be working in Blockland.
The above takes roughly 2 minutes.
My Blender setup:
- I resize the model to the correct size. It's a rather crappy setup so this step takes ~20 seconds.
- Set the stud texture repeating to the correct value for the brick size.
- Align the camera size and location so the brick fits the image nicely, render.
- Rename the PNG.
This takes about a minute per brick. The rendered PNG is ready for use.
If I wanted to get real fancy and stuff I could
everything above with Python so the entire process would just require the user inputting the brick XYZ sizes and reduce the time to ~5 seconds per brick.
Here. Take a guess which brick I rendered in Blender just now.

No thanks, I'll stick to my Blender setup. It's not perfect but it's close enough.
Did the job just fine for these 111 bricks.