These days, I keep a multiboot USB key in my wallet and it had proven to be useful on so many occasions. It does not take up too much space in the coins compartment because it is just slightly larger than a $1 coin.
The "Life Saver" USB Key
Several months ago, my sister found that she couldn't use her laptop. She had not used it for sometime already. We discovered that it was running an old version of Windows Vista that could no longer be updated. It was unstable and was constantly crashing. We could not installed a new version of Windows because the process would wipe the hard disc and she needed the data therein. Fortunately, we were able to use this key to boot into a Linux live-CD allowing her to copy her data to an external drive. I shared with her the benefits of Microsoft family 1TB onedrive storage and given her one of my family "shares". Hopefully, she will not run into this problem again.
$3 USB Micro SD key
There are many variations of micro SD adaptor in the market. I bought this particular one for less than SGD$3 from Shopee. With both USB A and C configuration, the key is more versatile. It can be used on newer devices that may not come with USB A. I was also able to use it with mobile phone for file storage too. Most importantly, it is small.
Ventoy, the bootable USB solution
I discovered Ventoy some time ago and it had become my go to solution to create bootable USB drives. I had also shared with my colleagues about this tool.
Creating the USB bootable key with this open source tool is easy. Just download the installation package. Then run Ventoy2Disk.exe. Choose the drive location of the USB key and click the install button.
Then copy the ISO/WIM/IMG/VHD(x)/EFI files to the USB drive and Ventoy will present a boot menu for me to select them. These are the iso image files in my USB key at this moment.
This is such a time save, there is no longer a need to burn DVDs / CDs or create USB drives for each Operating System.
For this purpose, I chose to recycle one of my old 16GB micro SD card. There is space for 6 Linux live-CD iso images. Obviously, with bigger micro SD cards, there would be more space but 6 live-CDs iso images is already an over kill.
Booting from the USB key
For my laptop, during powerup, I can either long press F2 to go into the BIOS setup or F7 to select the boot device. This may differ for you. Select to boot from the USB key.
After which, the Ventoy menu will appear for you to choose the OS to boot into. Select the installation disc or Live-CD you want.
Updating the USB key
There is a recent update to the Ventoy software (dated 17 Jul 2021). However, I have not updated my key and had used it to install POP OS 21.04 without any issues on Sunday Morning (25 Jul 2021). It is an experience I am considering to share. And when I eventually update the key, I will share the experience here too.