Imagine that you were building this all by yourself, and that you had to make the bars yourself out of raw metal. Here's the wrong way to build it:
Make one tall lead bar, and lay it flat on the ground in your workshop:
Cut a hole through the tall bar, and measure that hole.
Make a new bar that will fit through that hole:
Put that new bar through the hole and weld them together permanently:
Cut two holes in the horizontal bar, measure them, and make two new lead bars that will fit in those individual holes:
Insert the two bars into the horizontal bar, and weld them together permanently:
With a forklift, put this into a truck to move it to the location where it's supposed to be. (It's too heavy to move by yourself.)
With a pulley, make the construction stand upright and put it into the ground.
Discover that it won't stay up by itself, but if you put some blocks next to it as an emergency solution, it doesn't fall over:
Three days later, watch the structure fall over and break because...