Years ago, I came up with an acrylic bracket to keep food in the display tank instead of letting it float across the surface and into the overflow (thus down into the sump, wasted and uneaten). I called it the Eheim Chimney, as it was made to fit the Eheim Autofeeder system. Turns out it fits the Apex AFS just as nicely. I usually suggest the person simply put it on top of the overflow box since that's a great place where it won't be knocked off into the tank. If the overflow box doesn't have a lid, I can make that as well.
What about those rimless tanks, or tanks with an external overflow? I had a friend recently ask me to make one for his rimless tank. We looked at the clamp mechanism that comes with the Eheim Autofeeder, and realized it has enough room for a maximum thickness of up to 1/2" glass, plus the 1/4" acrylic I use. This is what it looked like on my 3/8" thick glass, once installed. It grips the tank and the acrylic chimney, and it was merely tightened snugly, not cranked down like a crazy man.
The chimney section has to be under the opening the food drops out. We placed it here for the picture, but most people would likely install it near the back corner. Most importantly to me, it had to have that clean look.
We tested it on my tank, and later he reported it worked perfectly on his. I may be making these to sell from my site in addition to the normal type.