I made a felt-board (also called a flannel board) for the twins when they were about 18 months old. It was really easy to hot glue some flannel fabric to a large picture frame and then cut out various shapes from craft felt for them to play with (the pieces stick on without glue and are reusable). I recently brought the felt board back out, and all three kids have been enjoyed it. Other than just being generally creative with it, I also made some Montessori-inspired sensory activities out of felt for them to work on...
The girls (almost 3.5 years old) really enjoy "building stairs" lately, so I cut them pieces of felt of different lengths for them to put in order. They can use them vertically to make stairs or horizontally to make a Montessori "pink tower".
I made a similar challenge for the kids by cutting out squares of different sizes to place in order.
Green squares of various sizes can be cut in half to make two triangles. I mixed them up, and L enjoyed the challenge of matching them up again. I plan on making some Montessori constructive triangle sets from felt, as well when I have the chance to print out some templates and cut more precisely (for these exercises I literally cut the pieces out as my girls were working on them so there was little time for precision).
I made the triangles intentionally green so they could double as evergreen trees:
We threw in a little Christmas and Hanukkah fun while we were playing with felt:
I love how versatile and easy felt boards can be! The girls really took over the felt board when I brought it out, but I think Baby H (15 months) will be enjoying it soon, as well.