I found some U-Tube videos of children songs that are so adorable. "Super Simple Songs". They feature some songs with rod arm puppets that are so cute, they called them Super Simple Puppets. The manipulation puppetry is outstanding. My grandchildren are big fans. Here is link to one of my favorites. Red Light, Green Light | + More Kids Songs | Super Simple Songs

Highest praise for job well done to these folks.

Yes very well done. Looks like they are  in  Toronto Canada.

Some of their puppets appear to have a curved mouth cut in head so that they always look like they are smiling. Sort of a cut upward instead of horizontal cut. I really like these pleasant looking puppets. I am surprised that the black eyes are so small and simple but it really works well. Grand kids have been with me for two weeks now and I have been seeing a lot of these videos. You can trust that they will be safe for your little ones which can't be said for many kids videos online. I am a big fan.

Most all patterns that are for this style of puppet have that built in smile.  I think you see it more in these puppets because of the skill of the puppeteers.  With the head tilted down just a bit so the eyes are looking into the camera and by keeping the mouth open just a bit even when "closed", it enhances the smile effect.  If you look at the Project Puppet gallery of puppets built with their patterns you see that some have the smile and others do not. The cleaner the execution of the build the better the smile will be also.

Ah Shawn. Good explanation. The elusive 'smile'. It is one I struggled with a decade or so ago. A character we made was from a cartoon with an exaggerated drawn smile, and we never could get it down quite right. The puppet eventually got stolen, so maybe there is an opportunity to redo it. I found that there was limited possibility to tilt the mouth plate down in the design to give that smile, but if you do it too much it becomes weird and hard to manipulate . I still haven't got it totally figured out. Anyone else got any thoughts on it?
   Snail, all the  material filmed is so catchy. I agree with you.

Addictive yes, but not overly annoying to adults, that is key.

Good points Shawn. The slightly ajar mouth does add to the smile effect as well as the forward head tilt. Eye placement is so important, they nailed it.

I like their "rosy" cheeks sewn on but I might just add them with blush circle rather than sewn on. They vary the skin colors, hair, and clothing details so they look similar but still each has it's own separate character. The grand kids are gone but I must admit I am still watching these cute videos. I think this is a good model to follow for preschool puppets.

Indeed, big props to them! I wasn't familiar with that 'show' but it's obviously done by people who know their stuff.