Oh Oh, make a trial square using all the suggestions you are getting. I thought if it were for yourself, it really wouldn't make much difference what size they turned out to be.
But a top with squares from more than one person could be a problem. Bet they won't all be the same anyway.
Let us know how this turns out. I have tried putting together squares made by more than one person and it can be a headache.
Good luck on your project, we will be waiting for a report on the results.
Carol J.