Step 1.
Lay
out the design.
(its hard to see, but there are red grid lines
drawn on part of the backing piece)
Step 2.
Cut
pieces of 1/4" thick styrofoam in the desired shape. In this case
a 2" square. Then glue the pieces to the styrofoam board with headliner
adhesive.
Step 3.
Now
its time to glue the fabric down. I spread glue across half of the
board and started to smooth the fabric down from the inside out.
The fabric has a foam backing, so you shouldn't press too hard. Just
smooth it down with your hands. When you get to the edges of the
two different heights, use your finger to direct the fabric into the corners.
Finish gluing the rest of the fabric, and trim.
(Forgive the color differences in the two pictures.
These were taken in our garage, not a studio)