A issue recently is I have been playing with some new distributions as I have been doing more development using linux as my desktop operation system.
Before I would commit to using a new distribution os my main laptop operating system. I have been trailing them as virtual systems on VirtualBox.
Some of the distributions only come on live iso images, with no installation application. So my solution was to convert the live iso image into a VirtualBox vdi. The process is only one command to convert the iso to a vdi file.
Locate the live iso image for conversion to a vdi file..
Once this is complete you want to add this to your VirtualBox machine. When you create your virtual machine, instead of creating your new your new vdi file, load the newly created vdi file.