These are several lengths of 20-20 that can be connected with one M3x20mm screw at each joint. I have also created male and female ends in case you need to end screw them with the typical M4 screw. If printed out of ABS you can use MEK (in the solvent section of many hardware sores) to fuse the joints while being fastened by the connecting screw to increase strength and rigidity
I have to give credit to Somaraok for making the original file. To be honest, I thought it was silly to print this because of the size and strength limitations of the plastic and printers, but I was mistaken. This profile is durable and can be assembled to meet required lengths.
The source for the original extrusion profile is here