One of my first projects built with struts. The struts are made from what is called 3/4" EMT. This is steel tubing about 0.922" outside diameter and about 0.050" wall thickness.
This stand is incredibly strong and lightweight. In fact it is so lightweight it is topheavy with the 65 pound vise on top. A (hexagonal) plywood platform and 150 pounds of weights on the base keep it stable.
I started this project by buying the vise at Harbor Freight. The base of the vise has three mounting holes. I figured out how high I wanted the base to be above the floor and decided I wanted a triangular base. I thought I could run a strut from each corner of the base of the stand up to each mounting hole in the vise. I first tried to model the geometry in a CAD program but it wanted things to be perpendicular to each other and did not allow me to easily draw a cylinder between two sets of [x, y, z] coordinates. I then used POV Raytracer to model the geometry. I soon realized I had a minor problem. Three of the struts were intersecting in the middle about half way up. Adding the vertex (joint) in the middle fixed that. Here is the final POV Ray source code.
The "cylinder" statements starting about halfway down in the code are where the interesting action is. Here is the resulting image:
When I was satisfied I used the numbers in the POV source file to calculate the strut lengths. Then I fabricated the pieces and bolted them together.
I learned a lot about building with struts while doing this project.
In particular if two struts come together at too small an angle the bodies of the struts will interfere with each other.
Also the struts are very strong in torsion (twisting) so it is important to get the angles between the tabs correct. (If the ammout the tabs are bent is off a little it doesn't matter.)