In this picture, notice that Ken has the diameters of the proposed bamboo struts written on the outside of the hubs prior to drilling the holes.
Ken is using various size hole saws to drill the appropriate hole size in the outer collar to match the bamboo strut diameter.
This hub is accomodating "small", "medium", and "large" bamboo struts, as you can see written in small print on the edge of the collar.
I think this is "pure genius". Wow, I am still amazed at the creativity displayed here.
Thanks for the pictures, Ken.
Many blessings to you and to your work with the homeless shelters.
John Hurt.