Probably the preferred method for cutting intricate or thick aluminum the water jet focus a very thin stream of water mixed with abrasives at extraordinary pressures and very high speed into the sheet metal.
Cutting aluminum sheet clean.
How to cut thin sheet metal and keep it flat.
This jet of water eats away at the metal and leaving a clean smooth edge.
Set the piece of aluminum on a table or over sawhorses and position it so the cutting area has open space underneath it.
2 mark the start and stopping point of your cut.
Place the fracture line over the edge of a table and bend the overhang slightly downwards.
The illustrations are for a small bracket but i have cut 3 foot.
If you use metal shears to cut thin sheet metal such as duct metal it curls and can be difficult to flaten properly.
These photo steps show that it can be done using a utility knife.
Sheet aluminium can be cut without the need for a guillotine or tin snips which tend to deform the metal.
With the aid of a straight edge and a sharp knife score both sides of the aluminium sheet.