Hey there! So you've stumbled upon a 3DM file and you're not quite sure how to open it, right? Don't worry, I've got you covered with some quick tips on how to access those 3D models. Here's what you need to do:

1. First things first, you'll need the right software. 3DM files are commonly used with 3D modeling programs like Rhino or CAD software. Make sure you have one of these applications installed on your computer.

2. Once you have the software ready, simply launch the program and go to the 'File' menu. Look for an option like 'Open' or 'Import' and select the 3DM file from your computer.

3. If the file doesn't automatically open, don't panic! Sometimes 3DM files can be associated with a specific application, so you might need to right-click on the file, choose 'Open With,' and then select the appropriate software from the list.

4. And there you have it! Your 3DM file should now be open and ready for you to explore. You can navigate through the 3D model, make edits, or simply admire the design.

So, next time you come across a 3DM file, remember these simple steps and you'll be able to access your 3D models with ease. Happy 3D modeling!