How to make mineos iso?

Everytime I download the mineos iso it comes in multiple folders.

A when you download the file, don’t let the computer mount it or extract it. Instead leave it as an ISO file and either use a disc burning software or image writer for USB drives. ISO to USB works well, but I haven’t tested it recently (my boxes are old and couldn’t boot.) There’s a ton of disc burning apps out there as well.

It comes in a rar file and In the file is two folders named isolinux and casper, how do i make the iso

Can you share the link you used to obtain the ISO?
If it’s not from here, that is: MineOS Wiki
It shouldn’t be in a .RAR file.

In all likelihood, you simply have .iso files registered to open with winrar/7z/etc. You definitely downloaded an ISO, you just may not see the extension and therefore you’re opening the contents.

You needn’t make the iso. You can find a DVD burning software or a DVD-to-USB program like rufus to make it bootable.