Thin-walled tube of soft metal when you try to bend often creased. To avoid this, they are usually pre-stuffed with sand.
With the same purpose, you can use another method: navit on the future site of bend copper or aluminum wire – turns will not allow the tube to wrinkle at the bend.
The same result can be achieved using a suitable inner diameter of the spring.
Recommend to read
NOT WITH A HAMMER, AND A CLAMP
It happens that the edge of the sheet material must be fixed with nails. But to use a conventional hammer, as this can damage the surface. Come to the aid of an ordinary clamp. She...
HELPFUL BRUSH
To clean the inside of the tube or a long narrow cavity is not so simple. This can help "brush" like how to wash their bottles, only to make it necessary from segments of a steel cable....