I used extruded aluminium rod (T-slot).

Its strong, sturdy and can be built with just an allan key. The slots allow easy fitting of attachments and joiners such as feet, handles, hinges, fans etc. Most suppliers will cut your order to size if you dont have an angle grinder. As no drilling or riveting is needed, you can take the rig apart to extend or modify very easily.

https://ibb.co/bQ35sH
https://ibb.co/iv8kRc