Padding the Dividers
1/2" foam needs to be glued around each of the Plexiglas dividers. I've never used this combination of foam, Plexiglas and adhesive before. The smallest divider is the very short one in front dividing the narrow accessory pocket in two. It's real purpose is structural, to keep a long divider that came with the case pressed up against four longer Plexiglas dividers on the other side of it. If it were to bow too much away from them, and it is somewhat flexible (more so than the Plexiglas), the dividers could slip out of the slots. It's small enough that I can work with it easily, and if I need to strip off the foam and start over with Plan "B" (a different adhesive), I won't have wasted much adhesive or foam.
I cut a 6" long by 1-1/2" wide piece of foam to wrap around the top and sides of this divider. Cutting it the same width as the divider allows wrapping it around a little more precisely and I can trim off some to expose enough Plexiglas - about 1/8" - to fit the case slots (around the inside edge and on the dividers it came with) after the adhesive sets.
Then I put some adhesive on one half of it and pressed the Plexiglas divider onto that side.
After that I put some adhesive on the other half, wrapped it around and used a small scrap block of wood to hold it down.
I'll know in the morning if the adhesive will work well enough to hold the foam firmly to the Plexiglas. If not, I have Plan "B" and a Plan "C" which are two different adhesives that are supposed to work on many different materials, including foam.
Now that the concept was demonstrated with one piece of foam, the next step was cutting out all the pieces of foam to cover all of the dividers.