I tend to overbuild just about everything we tackle but I dislike failures intensely. I'd rather spend a little more time and effort to do things right once. It is just one of the things that separates our work from a lot out there.
For our house project we created sign for many of the trades and suppliers. They are lined up out front for the duration of the project. When it is done they will be given to them for their own use.
The signs measure about four feet wide. Each has a steel frame laminated inside for maximum strength.
I routed the sign in three layers. The front layer was from 1.5" 30 lb precision Board. I covered that is the previous post. The middle layer was routed in two pieces with slots cut to allow the 1" x 1" square tubing to fit inside the sign. I cut and welded up the steel frame in a few minutes.
Once the welds had cooled it was time to start the gluing process. I used PBBond 240. It is a one part glue made by Coastal Enterprises. I dumped a puddle on the back sign piece and then spread it out with a stir stick. Old hotel key cards work great for this purpose. Then I misted the sign with a water sprayer to activate the glue.
The next layer (middle portions) of the sign were lined up and laid into place. THe welded steel frame was also laid into place at this stage. More PB BOND 240glue was spread, sprayed and spritzed with water.
Then the routed face of the sign was paid on top and everything lined up perfectly. Lots of clamps are critical at this point. The glue tends to bubble up as it activates and will expand between layers. The first time I used it I thought some heavy weights would do the trick. when I came back the next morning the sign layers looked like a deck of cards as the glue had expanded and then twisted as it dried. I learned that clamps were necessary to keep things in line and the more clamps are much better than less.
Properly glued and clamped the seams are all but invisible and hold forever.