Why is the sheet metal factory reluctant to buy section steel Meet many sheet metal factories, your rack if you use the structure of the square tube, he will ask you to modify the plate bending parts

Steel profiles that can be found in manuals may not be used in large quantities in practice, so production and manufacturing will become less and less. Sheet metal manufacturers will not be easy to buy on the market to your specified profile, or must go to customize, in this case, in terms of time and cost is not as cost-effective as using their own bending plate parts.