Open your original file in Inkscape
Then Save As
You should include your name and the project type so it is easy to find on the usb, and amongst your files. You should also include your preferred colour that you would like your keyring cut out of.
i.e yourname_character_lasercutter_3D.svg
A good digital technologist is able to take lessons and ideas and adapt them to their own projects.
This tutorial uses Tinkercad but you should be able to manipulate the ideas to Inkscape:
https://www.instructables.com/Plywood-Monsters/
This shows how you might go about deconstructing a monster into a number of layers and reconstructing it into a 3D character.
The easiest way to get started is to change all of your design to a stroke.
Select everything in your vector (Ctrl + A)
In the Fill & Stoke panel
Turn off Fill
Turn on Stroke. To begin with make the colour black if not already.
You may need to clean up your design at this point
no duplicate lines (the line tends to look darker compared to others, you can always select, delete and undo to check)
shapes should be whole. i.e. not multiple lines grouped to make a shape.
If you want to use the etch fill shapes have to be whole i.e. the line is connected the whole way with no gaps.