Making a multi boot installer SSD with OLD Mac O/S

I have got it down to 50-100mb over for each installer, all working fine, It is only Monterey on-wards that have updated installers occasionally... The remaining space has a Windows 11 to go partition, and all the "updates for the OS's that need doing after installation. plus some software. My question was how to get the 10.4 to 10.8 installers into .app installers, IF at all possible?

@livfe - Guess that wasn’t clear in your Q.

As far as the unused space the 32GB thumb drive as beyond the installer. It’s needed! Here it’s where the installer de-compacts the components for your system. While you could use a smaller drive every time you use it it wears the flash cells as the installer will reuse the space over and over again as it runs. So a few times no big deal, but do you want to bet the cell killer god? As one day when you need it it won’t work. I’ve used 8GB, 16GB and have found the 32GB are the most dependable for this task. Remember I’m a fixer who often uses these. If your like me then it’s a good investment for a few dollars. I can get a good set of five for less than $20 USD.

OK, did you slide down to the bottom of this Apple T/N How to download and install macOS I haven’t needed to build a new drive is so many years! I think I just made it as a bootable drive with its own install. Don’t get lost in the files extension .DMG will run natively.

@danj Yes I know you guys a far far more experienced than me, but the new drive is of course formatted and empty of an installer, so how would I get it to install from a .dmg file with no O/S installed to open it? Or have I missed something? I have also made another EL Cap installer on a 32gb USB, downloaded from the app store as a .dmg, run it, it made a .app in my applications, when I do the terminal commands I am now getting - Erasing Disk: 0%... 10%... 20%... 30%...100%...

Copying installer files to disk...

The copy of the installer app failed.

@livfe - OK, that’s different! It’s been years so bear with me! Do you have an option to point to a drive in the process? Again I set one up way back and I just don’t remember how I did it.

@danj Yes at one attempt it pointed to the ADATA SSD to install on, took ages, then get the error cannot install.... Trying with a Samsung 256 HDD soon.... failing that, would installing on another MBP 2012 then transferring the HDD back to the 2008 work or will I get the dreaded ROM or EFI thing all over again? I seriously want to get shot of all these older than 2012 models ASAP.

Yes aware of this, I just would like to know how to get the .app installer (Or the way to make these listed below onto a USB to install with)

OSX 10.4 Tiger DVD.iso (Not so important)

OSX 10.5 Leopard DVD.iso

OSX 10.6 Snow Leopard.dmg

OSX 10.7 Lion DVD.dmg

OSX 10.8 Mountain Lion.dmg

FYI - there are two builds of Tiger one for PowerPC and another for Intel systems like 15” MacBook Pro 1.67GHz Core Duo and OS X 10.4.5 Tiger Intel Installer DVD (Retail)

Heres the Snow Leopard 10.6 Snow Leopard install there is no need for Leopard 10.5 . And most systems support Lion 10.7.

OK great, I am getting them now.... I got the select language option now on Yosemite ..... which of course failed (Downloaded from apple) corrupted OS.... yay

Then next attempt, got the progress bar, then a bunch of black writing similar to a terminal command behavior and it auto shut down.... making a 32gb USB of EL Capitan now trying this.....

we should be in here Installing El Capitan on a stubborn 2008 MacBook in 2024