If you have the table temp already created, you can do something like this:
INSERT INTO temp4
SELECT temp1.*, temp2.*, temp3.*, *
FROM temp1, temp2, temp3;
put that into a new query in SQL view, save it, then run it, but be carefull, you may need to modifiy the statement to avoid duplicates, I would also backup the data you have to make sure it runs the way you want.