Oh that sounds fun
It could be dry or wet.
For traction, force and speed you could line the base of the tin with paper. Add paint to the inside of the lid and use a selection of items to dip and roll, or not as may be. See what impressions the objects make as they track across the paper - fir cone, tennis ball, small car, square block ... See if the items slow down when they have more or less paint on them. What colours mix together, and notice the lines & patterning the points of contact make - where object meets paper.
Or fill with a box of cornflour, a bottle of water and pipette of food colouring, mix, squeeze and examine the medium as it's stirred ...
squishy liquids
Other dry themes could be linked to the senses ..
Scented items to experiment with, this helps examine body parts and their functions. Maybe include a face jigsaw where the features can be assembled to form a whole.
Noisy items - loud, quiet, vibration, tone, pitch, echo, space - maybe have bands to strap across the opening of the tin & twang like guitar strings, upturn & use drumsticks ..
Magnets
Mirrors and light
Have a look through the preview of
science in the early years for ideas of how science is all around
If you follow children's interests you could also plan the tin to extend on possible learning.
Have fun & let us know what you do xx