To be able to manage painting the finer text I left the cut pieces attached to the urethane foam that I cut them from, this way I didn't need to handle each piece individually as I painted them.
Using self tapping tech screws I tapped them into the diamond plate back ground then cut the heads off with my air powered die grinder.
Then it was just a matter of using some silicone adhesive on the pins and the back of the letters to attach them.
For the letters that were spaced off the diamond plate I used nuts on the pins as a spacer.
I had to make a paper template to position the individual letters and carefully apply a continuous bead of silicone to the back of the letters and place them on the diamond plate.