MultiBootUSB project - tested and works. I only use it to boot a single instance of a TC iso however. Used the TinyCorePure64-11.1 iso.
Found a nice replacement for YUMI-Uefi. Intended for those experienced with TC and recognizing that this is outside the norms of support,
not to ask devs questions about something they are not responsible for! YOU are.Tried the latest MultiBootUSB burner ver 9.2.0 for both windows and Linux. Works great on all my 64 bit machines, including the very modern uefi-ONLY box.
Unlike simple dd'ers which just transfer the iso's to a stick, MultiBootUSB (like YUMI) makes big changes to the stick - most notably the use of other bootloader menus. Fortunately, the last menu is the standard TC menu, and allows you to change the kernel cheat-codes, and the usual TC grub.cfg is in control as usual.
And unlike the latest YUMI, it gets the filepaths correct!
Sure enough - all you have to pay attention to when you look at the stick it builds, is everything BEYOND
/multiboot/TinyCorePure64-11.1
for example and do the usual things. Rename cde to tce, adjust your grub.cfg to your likeing, etc. Hide your eyes to what lies before the /multiboot directory.
I actually always prefer just to move the entire cde directory to the root directory of the stick and rename that directory to tce in the process.
If you made the stick on Windows, you may want to clean up some dos ctrl-M line endings for grub.cfg seen with the less pager with a simple
sudo dos2unix ./grub.cfg
The gui interface in both windows and linux may seem to stall at first - but simply wait until you get the notification it is finished. At first it seems like the progress bar isn't moving and nothing is happening, but if your drive has an led on it, you'll see it is working. Just be patient.
Select drive.
Select iso.
Install Distro.
(don't shoot yourself in the foot with other options, unless you know what you are doing.)
That's it, other than being familiar with TC being very beneficial. Once I got some dependencies fixed for the Linux version (mtools, some python tools), I was glad to see the same interface.
So for now when I feel lazy, I think MultiBootUSB is now my 3rd party burner of choice. It seems to get everything right.
BUT - like all 3rd party stuff that the devs of TC have no control over, the next version may break so don't cry.
Again, familiarity with how TC works in the first place is recommended.