how to create bootable mac os x lion usb

I don't think you can. Even all of Apple's instructions for creating bootable macOS USB installers mention needing at least OS X 10.6+.

Plus the link provided by @PRP_53 is from 2011 when the Lion installer was much different so I doubt it will even work since the Lion installer today that you receive in the DMG file is not the true installer. You need to run that .pkg file to actually extract the real full installer from the downloaded DMG file. If you can do that with OS X 10.5, then you can try the instructions @PRP_53 linked. However, that extracted installer is not quite the same as it was 10 years ago so I'm not sure those instructions will still work today. I'm definitely curious though.

FYI, make sure to carefully read all the steps in the following Apple article for downloading and extracting the real installer from the downloaded DMG file (applies to macOS 10.7 to 10.12):

How to download and install macOS - Apple Support

thexboxgod360 wrote:

I want to make a bootable usb of mac os x lion for a 2006 macbook, that is currently running amc os x 10.5. can someone help?

Perhaps this link will prove fruitful

https://osxdaily.com/2011/07/08/make-a-bootable-mac-os-x-10-7-lion-installer-from-a-usb-flash-drive/