Not pyro-based fun, BUT a fun project nonetheless. Take a laser-pointer(s) and at multiple intervals map the trail of the reflection. Find out where the focal

Not pyro-based fun, BUT a fun project nonetheless. Take a laser-pointer(s) and at multiple intervals map the trail of the reflection. Find out where the focal point is, and post for fun. For bonus geekiness use some dry-ice to better illuminate the path.