I'm in DC as an Albert Einstein Distinguished Educator Fellow at the National Science Foundation. I was invited to do one of my physics shows at USA Science and Engineering Festival as well as TJStar. Some of my materials, I brought with me. Some I had shipped. I didn't ship 100 pounds of broken glass. So how will I walk on broken glass? My friends at the Foundation and in the Fellowship have been bringing me wine bottles and I have been breaking them into bits.
My SF bed of broken glass is made of window glass that I got from Urban Ore. Broken window glass is sharp but flat. Wine bottle glass is less sharp but curvier and doesn't lie as flat. It also seems to make more little shards. So far so good, but I'm watching out.