Suggestion - editable space bar

Double taping space bar can make a period. Would it be possible to extend the feature, making it possible to choose a different command (we all have different communication techniques) like a dash (-) or with spaces ( - )... a + sign or whatever. Maybe a small point, but in the search (hunt) for faster and more intuitive typing happits, using a fragment of a second instead of 2 seconds, counts a lot in the long run :).