So sorry to hear all this, Tiller Girl. Without wishing such situations on anyone, it's nevertheless helpful to find others in a similar situation, if that makes sense & doesn't sound awful. Your reason for not wanting your OH to go into respite care is totally understandable.
Great that the colouring books work! If only my sister could find some activity that would keep him amused when bored, so she could get on with something else for a while - even paperwork. I think, in fact, she tried the colouring books some time back but either he couldn't manage even those or else decided they were "silly" too. Might be worth another try now, because he will most likely have forgotten the last attempt and could be more receptive now. However, drawing or art was never his thing in the past. I know you don't need skill per se for these colouring books, but I do wonder if it's harder for PWDs to take up something they've never done/had natural ability for in the past? There's no unconscious hard-wiring, if you like, to draw upon, and now it's too late to learn something new, even if it's simply colouring within lines & doesn't matter if you mess it up.
In his youth, my BIL played rugby so I think he must have had good hand-eye co-ordination. Sometimes, these days, he doesn't see what's right in front of him (thinks his plate is empty when there's still food on it, or can't see the dog that's on the end of the lead in his hand). But at other times he can surprise you. Last time I was over (May), we were walking through woods with the dogs. One of them loves to run after a ball and my sister has one of those ball-throwing thingies. Although BIL would lose track of where the ball landed, and not see it or think to pick it up if the dog dropped it at his feet, he was mostly very accurate at launching it from the gizmo. Even when the track narrowed, with deep vegetation either side, he managed to aim the ball straight down the track. So I wonder if that's because he doesn't have to think how to throw - he isn't learning a new skill. (Am not sure if they use this in the garden as well. Will check.) I may be talking rubbish of course - it might just have been a good day.
And thank you for your very kind offer for my sister to contact you. I'll ask her, although she has never been one for forums or social networking of any kind, so maybe don't hold your breath!