[kach22i]

I'm having flash backs - why did you do this to me?

I recall driving around in my 1966 Mustang, and also riding on my 1978 Honda Hawk going to all the fast food places and finding straws that fit snugly into each other. They were not all the same sizes, the straws for shakes were larger and the smaller straws fit into them. Plus the differing suppliers had slighly different tolerences which allowed even more combinations.

The base is in tension, the corners want to kick outward - all I had was friction on my side.

I laid a bridge of straws side by side on the flat top of the structure- just like a log raft. This made a continuous load for the bricks to rest on, and not a destructive point load.

Avoid point loads, distribute the load as evenly as possible.

You may not need as much diagonal bracing as you think if you make the straws double walled as I did.

Above all follow the KISS Method (keep it simple stupid).