The answer is the thickness should be just over half the coin's diameter. At least according to Twitter and one of the responses to the first "answered before"

The answer is the thickness should be just over half the coin's diameter. At least according to Twitter and one of the responses to the first "answered before" source linked in the article: https://twitter.com/radu_nicolau/status/956926727971852290 https://twitter.com/radu_nicolau/status/956926727971852290