I'd like to see a sandbox like that. We could have a couple extra beside it as well. Pushing the button to refill is easy. Ive seen this done an worked well. Gravel could be one and snow and ice could be another.
Next time I would have them write their ign, rank and what they would like. Then you can distribute. Or have people with higher ranks buy for those. Or basic buy for basic. If the person doesn't get a gift for their other then they don't get theirs or take theirs and give it to who they were to get for.