So you want to open OBJ files in GIMP? No problem! While GIMP is primarily known as a 2D image editor, it does have some limited support for 3D models, including the OBJ file format. Here's how to do it:

1. Install the GIMP plug-in: GIMP doesn't natively support the OBJ file format, so you'll need to install a plug-in to enable this functionality. You can find various plug-ins available online, so do a quick search and choose one that fits your needs.

2. Load the OBJ file: Once you've installed the plug-in, you can then open GIMP and go to File > Open. Navigate to the location of your OBJ file and select it. The plug-in should allow GIMP to recognize and load the OBJ file just like any other image file.

3. Edit and manipulate: Now that your OBJ file is open in GIMP, you can use the various editing and manipulation tools to make changes to the 3D model. You can apply filters, adjust colors, and even add 2D elements to the composition. Just keep in mind that GIMP's 3D capabilities are limited compared to dedicated 3D modeling software.

4. Export your work: After you've made the desired changes to your OBJ file, you can then export it back out of GIMP. Go to File > Export As and choose a file format for the output. While GIMP may not directly support saving back to the OBJ format, you can convert the file to a compatible format like PNG or JPEG.

And that's it! Opening and working with OBJ files in GIMP is entirely possible with the right plug-ins and a bit of creative thinking. Just keep in mind that GIMP's 3D capabilities are limited, so you may want to consider using dedicated 3D modeling software for more complex 3D projects. But for quick edits and touch-ups, GIMP can certainly get the job done. Good luck with your 3D editing endeavors!