I've just found that I keep coming across the number $28$.
Next Year's calendar for February:

then there's my set of $28$ dominoes:

So, why don't you explore this number? Find $28$ flat shapes the same and put them together in some way.

Here are some I found using circular discs, octagons, hexagons, triangles and pentagons.

You may like to try $28$ cubes and get something like this:
or put together to make a caterpillar with changes at the ends.
Let us know what you come up with and what you notice.