Texture Picker
The texture picker is very useful when making models for your 3D printer. It allows getting the texture name of textures used by blocks in the world, simply by (sneak-)activating them with the tool. Disclaimer: for blocks that use special rendering, such as chests, this may not work.
While this is handy for quickly looking up texture names, it is good to know that you are not limited to the textures that can be picked with the analyzer. As long as you know the name of a texture (and it is a block texture), you can use it in your 3D prints.