The easiest thing to do would be to package the pre-configured vagrant box and transfer the .box file to the other machine, add the box and run vagrant up.

So the steps look like below:

1. Package the pre-configured box => vagrant package --base preconfigured_vm --output /path/to/mybox.box. Note that as per the docs, the --base option should be the UUID of the machine, or the name VirtualBox gives the machine (found when opening the VirtualBox application).
2. transfer the box to the computer by using scp, rsync or whatever... (you also start a web server quickly by using python -m http.server PORT or ruby -run -e httpd /path/to -p PORT)
3. Init and start vagrant init preconfigured_vm /path/to/mybox.box
4. Done