Aluminium is a lightweight metal that can be easily moulded and bent for construction and remodelling purposes. To bend a sheet of aluminium, you need to provide direction to the aluminium sheet with a superficial cut that the fold of the bend can follow. Once you are able to bend an aluminium sheet, you can create 90-degree angles to mould the sheet as well as create guidelines to create symmetrical sides and straight cuts.
Clamp the aluminium sheet onto a workbench or a solid surface. Make sure the aluminium sheet is clamped securely to prevent it from sliding when you are cutting it.
Place a straight edge on the area of the aluminium sheet that you want to become the crease of the fold. Mark dots on the sheet metal with a marker where each end of the straight edge meets the metal. This is to ensure that you keep the straight edge inline as you make a superficial cut on the aluminium sheet.
Hold the straight edge down onto the aluminium sheet securely as you run a razor blade lightly along the length of the straight edge. Do not cut all the way through the aluminium sheet, but just enough that you make a superficial abrasion that you will be able to use as a folding guide, but will not be as obvious as a dark marker line.
Remove the aluminium sheet from the clamp. Use your hands to grab opposite ends of the aluminium sheet and begin to bend the ends toward one another by allowing the abrasion made with the razor blade to give way and become the crease of the sheet fold. Continue to press the end of the sheet together until the sides of the sheet create a 90-degree angle.
Wear gloves on your hands to protect them from the aluminium sheet's sharp edges.