Just as an FYI, the legos are top-rack dishwasher safe. I put them in a mesh laundry bag so that the dishwasher spines poke right through.
I am a children's librarian and run both a
Lego and a Duplo group, so I now have an honorary PhD in cleaning the darn things!
OTOH, what a great solution to his building problem! I know it's hard to be proud when you're reminding him not to mix gummies and toys - or to stop laughing.
You may want to take a moment to write down how proud you were at this moment and stash that note away with the pictures. In a few years when you find it again, it will make you smile and remind him of how much you care about him, even when he's doing something you're not crazy about. (Teen years, anyone?)