So this plugin comes us to give one good tool to improve the 3D objects with normal map.
The developers tell us:
This is a plugin for GIMP version 2.8.x. It allows you to convert images into RGB normal maps for use in per-pixel lighting applications. The goal is to completely clone NVIDIA’s photoshop plugin, with a few new useful features.
First, you need to download it from gimp normal map google website.
Unzip the archive and copy files to your Gimp folder, see:
copy *.dll "C:\Program Files\GIMP 2\bin"
copy normalmap.exe "C:\Program Files\GIMP 2\lib\gimp\2.0\plug-ins"
The open one new image and fill with some drawing or text.
I used one with a transparent background. I draw with brushes and I add one text.
This plugin can be found at Filters -> Map -> Normalmap.
Take some time to understand how to working but the goal is to test yourself because most of the result depends on your drawing skills.
Also, you can see your result with 3D objects button. See the next image: