The Keneric KDE (KF5) thumbnailer is a generic thumbnailer. It is intended to be used when there is no dedicated KDE thumbnailer and there is a fast and simple way to get the thumbnail image (oneliner).
The Keneric can be used if you want to get more options to get the preview thumbnails.
The Keneric thumbnailer plugin is using a simple script to strip the thumbnail image from the file so the plugin can thumbnail the picture.
Included examples of:
* thumbnailing of .kra and .ora files
* thumbnailing of Blender files
* thumbnailing of Windows Metafiles
KReddit example: Preview of .stl files in Dolphin
KDE Forums folder preview example: folder.jpg pics display in dolphin
KDE Forums video preview example: Scripting KDE video preview thumbnails
The thumbnailtools is small collection of apps and example scripts to manipulate the thumbnail files.
HowTo / Readme
A short readme.html is included in the both archives.
Only guarantee: No harm intended...