Maybe use hands this time to create something beautiful?

santa face/ hat
get a copy of Santa with a hat leave it blank and get your 3.5 yr old to colour it then put there face on the middle part.
for the younger one Santa and reindeer stencils or just fold some card board in half give them both some Christmas stickers and texts/ paint and let their imaginations go.

Marble painting with christmas colours can be good – then you can cut out a christmas shape and stick it on coloured card. Kids could even decorate further with a gold metallic pen. There are some items in the art and craft section on this site about marble painting. I like it because it’s quick, easy, and any kid can do it and be happy with the results they get.

Last year we made Fingerprint Reindeer Christmas cards. I let my 3.5 year old draw the details (antlers, legs, nose) (I did do one first so he knew what to do)

How about fingerprint light/baubles on a string
or christmas trees with fingerprint baubles