Is there a way to access my real hard drive space (NOT the space in Cubic) or my USB stick?

You can create your Cubic project on a mounted USB stick or other mounted disk, as long as it is formatted with a Linux file system such as ext4.

You can't use an optical disk like a disk.

If this doesn't answer your question, perhaps I did not understand it...

Would you please clarify your question?
When do you need to use additional space? (While customizing an ISO using Cubic, while booted into your Customized Live ISO?)
What do you want to use your hard drive space or removable drive for?
Give an example of a scenario so I can better understand this question.

I was asking because I have a lot of big files on a USB disk that I want to install by default, which includes Windows games, DOS games, basically big files that I want to put on the Cubic ISO that I have saved on my other computers, my current Mint hard drive and USB keys.

Before I begged the question, they can't be transferred unless I put them on my Mediafire cloud space.

I apologise for the trouble in asking, but that's basically what I want to do.

This question was expired because it remained in the 'Needs information' state without activity for the last 15 days.

So is there a way?

Couldn't you just copy the files into Cubic directly from the USB?...

1. Create a directory in Cubic, such as `/opt/files`
2. `cd /opt/files`
3. Plug in your USB stick
4. Open your USB stick in Nautilus
5. Drag and drop your files onto Cubic

If you want to copy files from a remote machine, simply use the `scp` (secure remote copy) command:

1. Create a directory in Cubic, such as `/opt/files`
2. `cd /opt/files`
3. `scp -r <user>@<remote_host>:<file_or_directory> .`
    (Note the dot "." at the end of the command, representing the current directory to copy files to)

(See https://manpages.ubuntu.com/manpages/precise/en/man1/scp.1.html)

You can also take a look at the `rcp` and `rsync` commands.