Convert format, resize vdi and set uuid of virtual disks in VirtualBox

Convert format: VBoxManage clonehd source.vdi target.vmdk --format VMDK

Resize vdi: VBoxManage modifyhd YOUR_HARD_DISK.vdi --resize SIZE_IN_MB
 
Set harddisk uuid: vboxmanage internalcommands sethduuid "Windows 8.1 Pro.vdi" f8acb710-46c9-4d77-b7d3-52a1845d06c7