We've updated the Interactive Electoral College Tie Finder for the 2020 race. It shows all possible 269-269 ties for a given group of undecided locations (states and/or Maine/Nebraska districts).
11 states, as well as Nebraska's 2nd district were decided by less than a 5% popular vote margin in 2016. There are 64 possible ties based on that group of locations. An additional seven locations were decided by approximately 5-10% that year.
Use the tool to look at what ties are possible based on any combination* of these 19 locations. Over time, we'll update the locations in the tie finder as needed based on how the 2020 race evolves.