The following request would be helpful for those with open source 3D printers. Repetier-Host is a common software used to control these printers, but it assumes that it will be installed on a local machine rather than a portable drive. Having this software portable will help students who take their printers between home and school. This would also help people with 3D printers take the printer to a friend's house and show the technology without taking the computer along or messing up their friend's registry.
Program: Repetier-Host
License: Apache License 2.0
Description: Host controller for 3D printers.
Website: http://www.repetier.com/
Other: Keeps configuration information in registry. (Printer type and printer size, for example.) Registry information: Computer\HKEY_CURRENT_USER\Software\Repetier
Github Location: https://github.com/repetier/Repetier-Host
Program: Slic3r
License: Freeware / Slic3r is licensed under the GNU Affero General Public License, version 3
Description: G-code generator for 3D printers.
Website: http://slic3r.org/
Other: Keeps configurations in ?user data? and requires re-initializing working directory when moved.
github location: https://github.com/alexrj/Slic3r/wiki/Running-Slic3r-from-git-on-Windows
Repetier-Host controls the 3D printer, but Slic3r does the heavy lifting of converting an STL file into G-code. There are other dependencies for this software; they are listed in the Apache license of Repetier-Host. If this app request is very difficult due to all the dependencies, a portable version of Slic3r would be a great first step. Another software that uses Slic3r and may be easier to convert to a portable app is Printrun (https://github.com/kliment/Printrun). This does close to the same thing as Repetier-Host, but it doesn't have as many nice features (like a 3D viewer and real-time location reporting). Octoprint is another host software, but it is designed to run on a Raspberry PI.
Lastly, there is one more open-source 3D printer host and slicing software called Cura. I haven't used this software, but it may be easier to convert to a portable app because of fewer dependencies. The github location for Cura is https://github.com/daid/Cura
PrusaSlicer is not an official PortableApp, but it can be run in a portable way. Here's how...
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This seems to work fine for me, and I'm in a corporate environment (a college) where I am in the Windows group "users" and can't install my own software. It may be different for you.
I'm not sure what the PortableApps Platform will do. It is likely it will list prusa-slicer.exe, but running that won't store your settings in the --datadir location and will add to the Windows Registry. I also create a shortcut to the batch file and use that to launch the software. Perhaps the shortcut will appear in the PortableApps Platform menu.
-Rick.