Feeding time at the zoo

Colin wants to feed himself now. He doesn't have much patience for having a spoon shoved in his mouth. I put the food on the tray in front of him and he shoves handfuls into his mouth at his own pace. A good bit ends up in his lap, on the seat, in his pants, pretty much everywhere, so I just scoop it up and toss it back on the tray. Some of it anyway. He has such a good time with it how can I tell him no?
Maybe this is why Sharon wanted to wait so long to let Evan feed himself...