Hey, I read on here before, don't remember if I posted, but I wanted to say I LOVED this idea! My 2 1/2 son loves it too, and my dh even put in his 2 cents worth!
I couldn't decide on a tray for my son since a muffin pan's compartments just seemed too big and an ice cube tray seemed too small. My hubby came back home from the HARDWARE store with a plastic compartment tray meant to be used for nails, screws, etc. I thought it was a great idea- and it has a hinged lid so we can take it places. (We use plastic, I know some moms don't, but for those that do, this works for us!)
For apples I rinse them in lemon juice/water and they stay pretty fresh-looking for over a full day. The browning doesn't bother my ds though, it only bothers us adults.
I put yogurt in one part and salad dressing on the opposite side. A few graham cracker sticks, cheese cubes, apples, cereal with raisins (not Raisin Bran), grapes, carrot strips and frozen peas, organic cheesy guppies crackers, and tomato chunks and my son was good to go. He loved it!
We usually graze all day long in my home anyway, so dinnertime has never been a problem after snacking all day. I find that, not only does this improve my chances of getting my son to eat better, but it lessens MY workload during the day- important since I'm nursing an infant. I just stick it in the fridge during naptime after adding more grapes and yogurt, since those are the two that seem to go the quickest.