And my elder son decided to paint this little model. It might not look complicated, but it was small and fiddly. He spent a lot of time working on this.
Other ideas we have for the summer are to knit some simple dishcloths with my elder son, do an outing a week and then try to "present" it later, prepare for Harry Potter night - this, as you can imagine, has taken a lot of planning on the eldest's part!! He has made banners, prepared menus for banquets etc etc.
Another idea I thought of, and have not yet put it into play, is to engage the older two in family meal planning and once a fortnight each child is responsible for the planning of and budgeting for and some preparation of a family meal. I may try this over the next couple of weeks and if it works, make it a Sunday night regular!