virtualbox.org

Is there a way to create a VM within virtual box that will be available for another user on the host machine?

Yes. Put the VM folder into a shared folder ("C:\Users\All Users\VMs" is a good candidate). Then have each user "register" the VM, either via the "Add..." menu or by double-clicking the .vbox file. Check the permissions so that they allow read/write access. Only one user at a time...

Sharing a vdi file - https://www.virtualbox.org/manual/ch05. ... magewrites

Sharing a VDI file is quite different than common access to a VM folder. In the latter case only one VM owns the disk. Socratis' solution is correct (safer).