I saw this idea on Pinterest from Play, Create, Explore of using the suction cups on the bottom of bath mats to hold marbles as a fine motor and counting activity. We have some small bath mats from the 99p store, which are perfect for this.
It took him about a minute to complete the two shapes that I put out, so I quickly ran up and got some more.
It occurred to me that it would be great to have different coloured mats to use as a sorting or matching activity. Or you could even colour the suckers with a sharpie to encourage matching patterns. Another idea would be to complete one shape yourself with a specific pattern and ask your child to copy the pattern. Otherwise just simple placement like we did is great fun anyway.
This activity encourages counting, shape recognition, spacial awareness and develop fine motor skills. Its super easy to set up, and clean up, and has lots of opportunity for expansion.