Couldn't eat it - it took four days to set (all the separate layers) and by the time it got home tonight it was a bit scrambled. There is a jelly in the fridge for eating but it didn't set in time for tea.
He made a plain jelly in a small mould, then he lined a Tupperware tub with playdoh, covered it in cling film and put the first jelly in the centre. Then two pints of lime jelly in the gap. When just set, put in two green midget gems and one black one (they are some sort if important bots). When that was all set, took out the jellies and playdoh, replaced in tub and poured in lime jelly with additional green food colouring. For an 11 year, he really worked hard on it!
...only problem is, you (sorry "he"!) has set a standard now that he will have to keep up for the rest of school. My view is start low so that you can then get extra points for making an improvement and for extra effort etc.