This is a plug-in for GIMP that helps creating printable box wraps for board games. The manual process of creating a custom wrapped box for board games is described in the excellent tutorial by Pixelart Meeple on BoardGameGeek. This plug-in automates some parts of the process.
First make sure that your GIMP version supports Python plug-ins. If you use GIMP for Windows you should be fine. If you use GIMP for Linux you might have to install an additional package to enable Python support for GIMP. I had to install gimp-python on Ubuntu 19.10.
Next locate your GIMP plug-in folder. In GIMP's menu bar click on Edit/Preferences and then on Folders/Plug-ins. This shows you all folders where GIMP looks for plug-ins.
Finally copy the file boxwrap.py to any of you plug-in folders and restart GIMP. The plug-in should show up in the menu as Filters/Boardgames/Box Wrap.
Creating the printable box wrap is a two step process. In the first step you will create an unwrapped version of the box wrap. In the second step the plug-in will create two printable versions of the box wrap, one for the top part of the box and one for the bottom part.
Click on Filters/Boardgames/Box Wrap/Create empty template... This will open a dialog where you can enter the physical dimensions of the box.
Enter the box dimensions and press OK. The plug-in will now create a new template image for the unwrapped box with 300 dpi resolution.
The templates consists of one white rectangle for each side of the box. The rectangles are labeled TOP, LEFT, FRONT, RIGHT, BACK, and BOTTOM. In the top left corner of the template you can see the physical dimensions of the box. You will need these later in step 2. There are several guides that mark the edges and the equator of the box.
Fill in the graphics however you like. You can add or remove any number of guides and layers. Only the size of the image must remain the same.
This is an example of a filled in template ready for step 2.
Click on Filters/Boardgames/Create wraps from template... This will open a dialog where you can enter the physical dimensions of the box (again), the thickness of the material that your box is made of, and a few other parameters. The dimensions must be exactly the same as in step 1.
Enter the box dimensions and the cardboard thickness and press OK. The plug-in will now create two images, one for the upper part of the box and one for the lower part.
If nothing happens you probably have entered the wrong box dimensions. You can click in the menu on Windows/Dockable Dialogs/Error Console to open the GIMP error console. This should should show an error explaining what went wrong, for example
Template image has the wrong size.
Expected 4134px x 3602px (350mm x 304mm)
but got 4134px x 3590px (350mm x 303mm).
You should now have two new images that are ready for printing. Note that the flaps that wrap around the edges of the box were created by the plug-in.
There are several guides which indicate the interesting parts of the wrap including the flaps, the edges of the cardboard, and the parts that are on the inside of the box.
There are also marks for cutting and folding. These are covered by the guides so you have to hide those to see the marks. Click in the menu on View/Show Guides or press Ctrl-Shift-T.