Here is my design for a tower shield/quick release back shield. Questions and criticisms greatly appreciated.
First I took a 2x4' 1/2 in plywood sheet and drilled a lot of one inch holes to drop weight(leaving the middle section hole-free for rigidity). Then I a bolted on the handles and 4 rings(for the rope to turn it into a back shield).
http://flickr.com/gp/79907238@N02/456uT2
Then I added the foam, 3 sheets of blue foam on the front, 4 on the side, and one camp pad on the back. I alternated the foam on the face and sides to give it extra stability. Because of a lack of good DAP I used Super77. No tape was used.
http://flickr.com/gp/79907238@N02/67gu3M
http://flickr.com/gp/79907238@N02/4jqau3
http://flickr.com/gp/79907238@N02/Gzso81
Then I DAPed on the cover and used the left over canvas to reinforce the joints.
http://flickr.com/gp/79907238@N02/4o6S47
And here's how the back strap works. I put a rope through the top two rings, x it over my chest, bring each end through a ring and then tie it. For the quick release I just have to pull on the knot and it slides right off.
http://flickr.com/gp/79907238@N02/b7448d