If you're a Roblox developer looking to add custom 3D models to your game, importing OBJ files is a great way to do so. Here's how you can OBJ in Roblox using Blender and Studio.

1. Create or find a 3D model: First, you'll need a 3D model in OBJ format. You can create your own using 3D modeling software like Blender or find one online at websites like TurboSquid or Sketchfab.

2. Import the OBJ into Blender: If you're creating your own model, you can import it into Blender by going to File > Import > Wavefront (.obj). If you downloaded the OBJ, you can skip this step.

3. Prepare the model: Once the OBJ is in Blender, you may need to make some adjustments to the model to ensure it works well in Roblox. This may include resizing the model, applying textures, or simplifying the geometry.

4. Export as FBX: Roblox Studio does not support OBJ files, so you'll need to export the model from Blender as an FBX file. In Blender, go to File > Export > FBX and save the file to your computer.

5. Import FBX into Roblox Studio: Open Roblox Studio and create a new place or open an existing one. Go to the View tab and enable the Toolbox if it's not already open. Then, click on the Toolbox and select My Models. Click the Import button and select the FBX file you exported from Blender.

6. Adjust the model settings: After importing the FBX, you may need to tweak the model's settings to ensure it looks and behaves as expected in Roblox. This can include adjusting the scale, position, materials, and collision properties.

7. Test in-game: Once you're happy with how the model looks in Roblox Studio, you can test it in-game to make sure everything is working as intended. Publish your game and see how the OBJ model looks and interacts with the rest of your game environment.

By following these steps, you can successfully OBJ in Roblox and add custom 3D models to your games. Keep in mind that OBJ models may require some optimization to work well in Roblox, so be prepared to make adjustments as needed. Happy developing!