Peter
"I’m taking aluminum tubes away"
You can purchase the same (as aviation) sized aluminium tube & AN fittings, cheaper, from automotive shops that specialise in hot cars.
You will also need a pipe cutting tool (hardware store) and a flaring tool (eBay or similar) but be sure to get one with a 37 degree (not automotive/plumbers 45 degree) - better still borrow the right tool.
If you go the flair/AN fitting way, be sure to look at a few videos on how its done and practise, practise, practise, before trying to make the finished item.
Alternatively you can get a pipe beading tool to make a raised lip at the end of the pipe to prevent rubber hose from slipping off.
