Have you heard about Perler beads?
Over 100 examples in different categories.
I'd never seen them until my daughter brought home her creations from school. I thought it was kind of odd that she would be spending her time lining up little pieces of plastic on a board and then having the teacher iron them together. When I tried making one, I discovered how fun and worthwhile an activity it could be.
The little tiny flexible 'beads' are placed in rows on a small pegboard; eye-hand coordination gets a great workout. Making patterns teaches sequencing. I'm sure there are other lessons tucked in there. ("Patience sweetheart, Nana is looking for blues and greens---then I'll pass you the bucket." )
Initially, the placement of the beads was random, but she has graduated to patterns. She was super proud of the Fourth of July star she designed and made all by herself.
My daughter bought the big bucket of Perler Beads at our local Michaels Craft Store. I think three-year olds could manage if they had some help.
We are thinking about decorating the Christmas tree in Perler Beads ornaments. They would make neat ornaments and coasters. (Coasters? does anybody still use coasters?)
Perler Beading (I guess that's what it might be called) is a quiet relaxing activity. It keeps you wanting to try new designs therefore--- it doesn't get boring.
The only possible problem would be if the bucket tipped over and 6000 of those things got scattered!