How to bake glass and metal object on unique texture

This may be a bad answer, as I am not a Blender model-builder and am unfamiliar with Blender rendering emgines and shaders. However, as a general rule, you cannot combine diaelectric and non-diaelectric materials in a single texture file. At least, not that I am aware of. The general practice is to use separate material map sets for diaelectric materials (glass, etc.) and for diffuse/lambert types of materials. If I were making a model with wood, brass and glass components, I would make three different material sets. For something like a "sideboard" model, you could use very small (512x512 pixels) map sets for the glass and for the brass, unless the glass is etched (has a lot of detail) and the brass is etched or weathered (has a lot of detail). Then you could make the wood texture a reasonable 1024x1024 pixel size, or whatever size you need. Three material maps sets of these sizes should not overly burden any rendering engine.

Anybody, please correct me if I am wrong. In Maya Arnold of Maxwell render, I just cannot imagine how a person would go about creating a single texture file set that has diffuse, transparent, transmission, metallic and non-metallic properties for different areas of the single map.

for the glass, use an alpha map. Make sure that in the material settings you change it from opaque to alpha blend. and us mettalic map for brass. It is alittle difficult to do stuff like this in blender(that's why people buy texturing software like substance painter).

This is what is called "Complex material setup" (If I understand what you are trying to achive). You have diffuse, roughness, normal. To be able to use single texture with materials wood, brass and glass, you need RGB mask. RBG mask is another texture, baked from high poly model wich will tell what part of the texture is what material. So for example you have 2048x2048 cut in 4 512x512 boxes. First box 512x512 is red color this define what part of the texture will be brass, second 512x512 is green and this define part of the texture that use transparency/glass, third 512x512 is blue this defines wood etc etc. Its kinda hard to explain here on forum, I also don't use blender and I don't know how to setup that in blender, but I do know that blender support RGB mask.

I've used Blender pretty extensively. I assume you're trying to create a PBR material? I had trouble when I first started with PBR so I'll try to break it down as simply as I can. It sounds to me like your problem may be with the Roughness map, so I'll explain that a little more.

Diffuse - Base color/texture. Put the color of your wood, glass, and metal on this map.
Normal - This is faux geometry baked into the texture.
Ambient Occlusion - Faux Shadows.
Height - Similar to Ambient Occlusion, but this map can also be used to displace the geometry of your model.
Metallic - Black and White map to define areas of metal and non-metal. White = Metal, Black = Non-Metal.
Transmission - Same thing as Metallic. White = Glass/Transparent, Black = opaque.
Roughness - This map defines the intensity/specular of your other maps. This map is extremely important for your Metal and Transmission maps. White = Low Intensity/Specular, Black = High Intensity/Specular. Grey values are important for this map. What I mean by intensity is this; You may have a Transmission map to define glass areas, but if the roughness map is completely white in that area, the transparent area is going to have a very low "intensity" of Transmission. Same goes for Metallic. You have to use the Roughness map in unity with the other maps. If you want a shiny metal area, you need a WHITE Metal map with a BLACK roughness map. You can use grey-scale to adjust for scratches or dirt.

Thank you all for the help!
I will follow your advice, now I'm starting to get my head around it a bit more, although I know it will still be hard for me.

You are right, in Blender it is very confusing in the baking part, especially for beginners.

Thank you autumnborn!

Thanks to all the people who replied. I learned some good things from this discussion!

Through the Principled Baker add-on I was able to bake all the textures needed for my model.
Now the wood and brass look similar to the original materials.
The only problem is the glass objects. For this material it doesn't work. The glassware is reflective, but not transparent.
I don't know how to do it, surely I am doing something wrong, but I don't know what.

Thanks lockiabel, now the transparency is there, but there is too much of it! In the sense that it's like the glass isn't there. In fact you can't see it at all.

Sorry, I got a little confused.
If I connect the color node of the image texture to the alpha node of the principled, everything is transparent, even all the other meshes.
If I connect the alpha node of the image texture to the alpha node of the principled, the glasses are reflective but not transparent.

I solved the glass transparency problem. I hadn't colored the base of the texture color properly.
That's why the glass was not transparent.
Thank you all for the help!