Scribus is an excellent libre desktop publishing program.
I used to write a small postcard game for the “Wish you were here” jam, but it is suited to any job up to professional level.
inkscape should work, and its all vector graphics, so you can do things like clip images
I would probably use Inkscape or Krita.
I made some posters in krita for work. Worked okay. Just make sure you start with the good ratio in px for printing.
If you plan on doing it on a regular basis, you might want to try latex. This is going to be hard on the first one or two poster but on the long run it can save a lot of time...
Also, PosteRazor is great for printing a large wall poster from multiple smaller sheets(A4/A3 etc).
GPL3. Has an online version and a downloadable version.
Scribus ❤️
Paint.net if you're on Windows.
despite being a good paint editor for Windows, it is unfortunately not open source or source released (I thought it was as well):
However, citing issues with the open source code being plagiarised by others that had rebranded the software as their own and bundled user content without their permission, the availability of the source code was restricted
In November 2009, the software was made proprietary, restricting the sale or creation of derivative works of the software.
To be fair to the guy, I'm not even mad. There aren't many freeware programs that good and that ethic.
I've used Silhouette Studio for this exact thing.
The basic edition is free, and has all the snap to alignments you're looking for. The pro version ($100) lets you save as an SVG, PNG, or PDF, so printing what you make shouldn't be an issue. It's a lot more powerful piece of software than I expected it to be.
All about open source! Feel free to ask questions, and share news, and interesting stuff!
Community icon from opensource.org, but we are not affiliated with them.