Hello
Yes circular saw works fine I agree
That mandatory to stay in 1000 or 5000 or 6000 serie alloy as they are weldable without problems , 2000 and 7000 are not weldable by using TIG or MIG process , 1000 are pure aluminium so that the softer one , I use 5000 serie mainly
To help welding that possible to drill and tap some holes and use M4 screws , that allow to pre-assembly the box and make the welding process quicker and easier .
Regards
OS