Best kind of paints to use with toddlers?

[Craftycat3]

Hi all,
Looking after my nephew who is 18 months old at the weekend, and thinking of having a painting afternoon as he loves crafts. I tend to use acrylic paints and just normal brushes or patterned rollers with older children but wasn't sure what would be suitable for a little tot?

Don't mind mess, have plenty of newspaper and messy mats to put down, but was wondering what you use? Was thinking of maybe finger painting but as he's currently putting fingers in his mouth a lot perhaps that's not a good idea!

Thanks

CCx

I use acrylics with my toddlers. They are washable and just watch they don't eat it ( although it's ok if accidental).

Otherwise a watercolour set is less messy