I made a magnetic spinner which HANGS rather than being a top as shown here. In my case, additional weight REDUCES friction instead of adding to it.
My longest spin thus far (finally completed a few minutes ago) is 32 minutes 4 seconds. Figured I'd go online to see similar challenges, ran across this one - will investigate rules etc. later to determine whether to post here or start a new 'hanging' version, just thought I'd drop in...