So just to cheer them up, I thought I'd offer an update on my craft attempts.
(from left to right(well, roughly): haunted castle from the Charlie and Lola magazine, princesses from Klutz, various Christmas crafts, hearts garland from Kids Craft Weekly,sea monsters from Mr Maker, bits of Fimo, ladybirds and hearts card from Kids Craft Weekly)
Another wonderful discovery has been the Galt Silk Painting Kit. It's a challenge to find age-appropriate projects that an older child can complete beautifully if they have fine motor difficulties. With this kit, you make small dots of paint, which spread automatically and stop at the gutter. It's practically impossible to produce something which isn't very lovely.
And a further small tip for the truly talentless. I have found that even if you are completely useless, a cheat's way to be the kind of parent that you want to be is to pretend to be the kind of parent that you want to be. It fools a 4 year old. It fools an 8 year old. If you don't keep your wits about you, you may even fool yourself.