Arrange the twelve tables side-by-side - three on one side, four on the other Each table is 21.625" x 21.625" so the final dimension of your platform bed will be 86.5" x 64.875" - which is slightly bigger than a standard queen size mattress of 80" x 60" but once the bed sheets and covers are on the mattress, I haven't found it to be a problem.
I thought I might need to duct tape or otherwise tie the legs together but haven't needed to do it - the tables are totally staying in place on their own.
That's it - you now have your off-the-shelf platform bed for around $100 that you can take apart, move (even up and down flights of stairs) and put back together all by yourself at any time - no messing around with tape measures, hacksaws, drills, clamps and hammers in the garage for hours on end, no sweat and grime at all.
P.S.: I am also using an improvised mattress made out of eight $9 sleeping bags inserted into a zippered mattress cover to go with this DIY platform bed for a complete, inexpensive, portable, lightweight bedding solution. Details are at http://www.instructables.com/id/DIY-Mattress-Substitute-Portable-Inexpensive-L/