Comment by srean

Such a beautifully done site. I might be in love already . Many kudos.

I dropped in a suggestion to do one on an umbrella. There's a lot going on in these. One can study the differential geometry of surfaces. The mechanism design of opening and closing.

I find both the spring ones (push button) and the ones without spring quite fascinating. In fact the ones without a spring has implicit ones imposed by the bending of the spokes.