Parts like knobs and threaded rods are readily obtainable, but you might have difficulty find many of the components as 'ready to use'. What you are showing is a product manufactured for a particular purpose. You can probably source aluminum pieces that you can adapt but you might still be into cutting, threading, etc. I'm a fan of taking a product and using it for an unintended purpose but it often entails modification and sometimes a trade-off or two. Can you buy that holder as-is and modify it to your needs?