How to create a custom chamber sign?
Thank you, will try what you suggested.
I don't have the plugin for photoshop, so I went through the TGA state.
I see I will have to experiment a little more, hopefully I won't destroy what's already done 
//edit: I see that the vtf plugin cannot create multi-frame vtf files, as seen in readme
//edit2: well, now that I opened the older multi-frame file I used in my map before, I see that the quality is as good as it should be. So the crippled effect is made by applying the texture resized 
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You're right, the VTF plugin for Photoshop doesn't look as the one for Paint.NET. Well, then you have to do it the hard way.
I don't understand the problem you describe under "edit 2". Does it look bad in Hammer and/or in-game?
EDIT:
I tried to make a 1024x2048 texture and scale it in Hammer to fit the sign. It worked perfectly, both in Hammer and in-game. The only problem I see is the file size (10.6 MB).
I just wanted to do "edit 3" 
but you were faster 
so, now I did a little experiment and the texture looked fine in Hammer, even after resizing. But in the game it was crippled. I think I will cope with it by letting it be, it is not so bad.
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Looks better from some distance
(the forum won't let me add a second attachment for one post)
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The reason why it looks crippled is because you use the standard texture scale in Hammer (0.25). A larger texture will look better, but a 1024x2048 (scale 0.125) texture is 10.6 MB!
so you recommend me to re-do it from scratch by first enlarging the original psd file from the tutorial to 1024x2048 and then continue working with the new images exactly the same way as before, and in the end at the texture application use a 0.125 texture scale, am I right? 
i will probably have some time to try it tomorrow.
btw. the brush I am having this texture on, is of size 96x192 Hammer units.
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I'm not recommending anything. You have to choose between quality and file size.
oookay, so I did it... the new texture is 1024x2048 in size, and looks much much better, like the original. But the vtf file is 18,6 MB 
And when fit in Hammer (by pressing the Fit button), it has set some weird numbers for the face texture, see the attachment
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Yes, it's as I told you; file size vs quality. But what's wrong with the numbers? If you pressed "Fit", those are the values needed to make the texture fit the surface it's applied on.